Cement Industry Engineering-Holderbank Course(2 of 2)

"Holderbank" - Cement Course 2000

© Holderbank Management & Consulting, 2000 6/30/2001 - 10:34:34 AM Query:

Engineering / B07 - Eng / C01 - Power Supply / Power Supply / 8. STRUCTURE OF ELECTRICAL SYSTEMS IN A CEMENT PLANT

8. STRUCTURE OF ELECTRICAL SYSTEMS IN A CEMENT PLANT

Engineering / B07 - Eng / C01 - Power Supply / Power Supply / 9. INVESTMENT COST OF A CEMENT PLANT

9. INVESTMENT COST OF A CEMENT PLANT

Engineering / B07 - Eng / C01 - Power Supply / Power Supply / 10. POWER CONSUMPTION OF A CEMENT PLANT

10. POWER CONSUMPTION OF A CEMENT PLANT



Engineering / B07 - Eng / C02 - Power Distribution

C02 - Power Distribution



Engineering / B07 - Eng / C02 - Power Distribution / Power Distribution

Power DistributionFritz Richner

1. SUPPLY VOLTAGES

2. HIGH VOLTAGE TRANSFORMER STATION

3. MEDIUM VOLTAGE POWER DISTRIBUTION

4. DISTRIBUTION TRANSFORMERS AND MOTOR CONTROL CENTRES (MCC)

5. HIGH VOLTAGE EQUIPMENT

5.1 Circuit Breakers

5.2 High Voltage Transformer

6. MEDIUM VOLTAGE EQUIPMENT

6.1 Medium Voltage Circuit Breakers

6.2 Medium Voltage Contactors

6.3 Medium Voltage Transformers

7. LOW VOLTAGE EQUIPMENT

7.1 Motor Control Centres

7.2 Motor Control Interface

8. CABLES

9. POWER FACTOR AND ITS IMPROVEMENT

9.1 General

9.2 Power Factor Correction

10. ENERGY- / POWER-METERING

10.1 Metering for energy invoice

10.2 Metering for internal use only

11. SAFETY PRECAUTIONS ON ELECTRICAL EQUIPMENT

11.1 Introduction

11.2 ‘Touch’ Voltage

11.3 ‘Step’ Voltage

11.4 Safety Precautions in High Voltage Equipment Rooms

11.5 Preventive Maintenance

11.6 Precautions against Electric Fires

11.7 Maintenance of Temporary Installations during Construction and Erection



11.8 First Aid

12. ANNEXES

12.1 Power Supply Typical elements of a high voltage transformer station

12.2 Power Distribution Protective relays

12.3 Power Distribution Typical elements of a medium voltage power distribution



Engineering / B07 - Eng / C02 - Power Distribution / Power Distribution / 1. SUPPLY VOLTAGES

1. SUPPLY VOLTAGES

In the cement industry, the supply voltages from the utility power companies are in the range of:

♦ 11 kV (for small plants)up to

♦ 150 kV (for large plants)

In power distribution systems we distinguish between equipment for:

♦ ‘high voltage’ > 50 kV

♦ ‘medium voltage’ 1-50 kV

♦ ‘low voltage’ ≥ 1 kV

The design of the equipment (e.g. circuit breaker) varies according to the requirements of the differentvoltage levels and power ratings.

Note: The medium voltage range is very often also called ‘high voltage’, e.g. 6 kV high voltage motors.

Engineering / B07 - Eng / C02 - Power Distribution / Power Distribution / 2. HIGH VOLTAGE TRANSFORMER STATION

2. HIGH VOLTAGE TRANSFORMER STATION

Depending on the layout of the cement plant and on the type of switchgear installed this station islocated on the periphery or in the centre of a cement plant. For safety reasons a cement plant ispreferably fed by two incoming cables or overhead lines. The transmission, voltage can vary between11 kV and 150 kV and is normally fixed by the power supplier. The high voltage will be transformed to 4to 11 kV by means of preferably two transformers, one of as stand-by.

For power distribution system-arrangement see Fig. 2.1. For power distribution single line diagram seeFig. 2.2.

Figure 2.1 Example of a Power Distribution System-Arrangement

Figure 2.2 Example of a Power Distribution Single Line Diagram



Engineering / B07 - Eng / C02 - Power Distribution / Power Distribution / 3. MEDIUM VOLTAGE POWER DISTRIBUTION

3. MEDIUM VOLTAGE POWER DISTRIBUTION

The medium voltage power distribution is usually located in an electrical room in the centre of a cementplant, this is order to minimise cabling and installation costs (centralised MV-distribution).

However, depending on the layout of the plant, the MV-power distribution may be arranged in adecentralised manner, i.e. the MV-distribution might be located in load centres common with theLV-distribution transformers and motor control centres. For comparison of ‘centralised’ and‘decentralised’ arrangements refer to single line diagram Fig. 3.1.

Decentralised arrangements may result in the application of a higher quantity of circuit breakers,control equipment, larger electrical rooms, a more sophisticated protection scheme and requires asomewhat more costly maintenance. Costs for MV-cabling may however be smaller.

The medium voltage level normally ranges from 4 kV up to 11 kV. There is a strong tendency to usethe higher voltage of 11 kV; 50 Hz, resp. 13.8 kV; 60 Hz, because a higher working voltage results insmaller cable cross-sections (i.e. lower investment costs) and less voltage drops (i.e. less energylosses).

The distribution station is equipped with a main busbar, the incoming circuit breakers and the differentoutgoing circuit breakers to the distribution transformers and ‘high voltage’ motors. Distributiontransformer stations are located in the different load centres, namely the crushing plant, the raw mealgrinding plant, the kiln plant, the cement grinding plant and the packing plant.

All high and medium voltage equipment (transformers, cables and motors) has to be protected againstoverload, short circuit, earth fault, over voltage, etc. to guarantee a selective fault isolation.

Figure 3.1 Centralised & de-centralised medium voltage distribution typicalsingle-line-diagram



Engineering / B07 - Eng / C02 - Power Distribution / Power Distribution / 4. DISTRIBUTION TRANSFORMERS AND MOTORCONTROL CENTRES (MCC)

4. DISTRIBUTION TRANSFORMERS AND MOTOR CONTROL CENTRES (MCC)

Distribution transformers and MCC’s are located in the different load centres of the plant.

The transformers have a capacity of 630 up to 2000 kVA depending on the power requirement and alow voltage level of 400 V up to 660 V.

Distribution transformers are normally installed indoors in individual transformer cells.

The low voltage switch gear and MCC’s are located in electrical rooms of the respective plantbuildings.

Figure 4.1 Single line diagram‘Example of a load centre with distribution transformer and MCC’

Engineering / B07 - Eng / C02 - Power Distribution / Power Distribution / 5. HIGH VOLTAGE EQUIPMENT

5. HIGH VOLTAGE EQUIPMENT

The high voltage transformer station generally consists of following components:



Lightning arrestors (protect the substation against over voltage such as lightning)

Current and voltage transformers (measure the amount of energy consumed)

Off-load isolator (isolate a circuit at no load e.g. for maintenance purposes)



On-load isolator (disconnect a circuit at max. double-rated current)

Earthing switches (connect a circuit to the earth for safety reasons, during maintenanceactivities)

Circuit breakers (disconnect a circuit under load and in case of fault)



Busbars (form the electrical power circuit)

Step-down transformer (transforms incoming voltage to the plant power distribution level e.g.110 kV to 7 kV)

The following 3 types of transformer stations are mainly used:

♦ Outdoor transformer station with conventional switch gear:

Characteristics:

• biggest surface area required

• medium investment costs for high voltage switch gear

• time consuming for maintenance (cleaning)

♦ Indoor transformer station with conventional switch gear:

Characteristics:

• medium surface area required

• lowest investment costs for high voltage switch gear

• medium time required for maintenance

♦ Indoor transformer station with metal-clad, SF6, gas insulated or vacuum type switch gear:

Characteristics:

• smallest surface area required



• highest investment costs for high voltage

• switch gear

• needs the least of maintenance

Figure 5.0.1 110 kV Outdoor Transformer StationTypical arrangement with conventional switch gear

Legend:

1 Busbar system

2,6 Off-load isolator

3 Circuit breaker

4 Current transformer

5 Voltage transformer

7 Lightning arrestor

8 Power transformer

Figure 5.0.2 110 kV Indoor Transformer StationTypical arrangement with conventional switch gear

Legend:

1, 2 Busbar systems (double busbars)



1, 2 Busbar systems (double busbars)

3, 7 Off-load isolator

4 Circuit breaker


6 Voltage transformer

8 Lightning arrestor

9 Power transformer

Figure 5.0.3 110 kV Indoor Transformer StationTypical arrangement with metal-clad, SF6 gas insulated switch gear

Legend:

F5, F6 Incoming feeders consisting of off-load isolators, circuit breaker,

earthing switches, current and voltage transformers

F1, F7 Outgoing feeders consisting of off-load isolators, circuit breaker,

earthing switches, current transformers

F4 Buscoupler (double busbars)

Engineering / B07 - Eng / C02 - Power Distribution / Power Distribution / 5. HIGH VOLTAGE EQUIPMENT / 5.1 Circuit Breakers

5.1 Circuit Breakers

In high voltage installations mostly SF6 gas circuit breakers are applied. The low oil content circuitbreakers are still used but manufacturing will run out in the next years.

Figure 5.1.1 SF6 Gas Circuit Breaker3-pole circuit breaker with operating mechanism



5.1.2 Schematic function of arc quenching mechanism of a circuit breaker pole

5.1.3 Metal-clad, SF6 Gas-Insulated Circuit Breaker

5.1.4 Cross section of double busbar cable feeder:



Legend

1 Busbar with combined disconnector/earthing switch

2 Circuit breaker


4 Potential transformer

5 Cable end unit with combined

disconnector/earthing switch

6 Fast acting earthing switch

7 Control cubicle

Engineering / B07 - Eng / C02 - Power Distribution / Power Distribution / 5. HIGH VOLTAGE EQUIPMENT / 5.2 High VoltageTransformer

5.2 High Voltage Transformer

Large high voltage transformers have an efficiency of up to 99%. They are always filled with oil whichstill copes best with all insulation and temperature problems. To meet the requirement for a constantvoltage level in the cement factory under various loads and with varying voltage levels of the utilitypower supply, the transformers should be equipped with a tap switch which automatically increases ordecreases the secondary voltage in steps of about 1 to 1.5%. Large transformer are equipped with airor water cooling equipment (a 20 MVA transformer with an efficiency of 98% still produces a flow of400 kW of heat). Temperature sensors and the so-called ‘Buchholz-Relay’ protect the transformeragainst overload and insulation failures. The Buchholz-Relay detects gas bubbles which collect at thehighest point of the transformer, and thus gives a good indication of insulation or local overtemperature problems, in the transformer. The vector-group of a transformer is often Yd5, where ‘Y’stands for primary star connection, ‘d’ for secondary delta connection, and ‘5’ gives the phase relationbetween the two systems.

Figure 5.2 High voltage transformer



Engineering / B07 - Eng / C02 - Power Distribution / Power Distribution / 6. MEDIUM VOLTAGE EQUIPMENT

6. MEDIUM VOLTAGE EQUIPMENT

Medium voltage power distributions consist mainly of the same components as described in paragraph5. They are generally of the indoor type. Today draw-out type cubicles are commonly used. Differentequipment can be mounted on identical ‘trucks’. The trucks are easy to handle and allow a quickreplacement in case of a failure. The figure below shows a medium voltage distribution station.

Figure 6.0.1 Medium voltage substation

Figure 6.0.2 Typical arrangement with metal-clad SF6 switch gear



Engineering / B07 - Eng / C02 - Power Distribution / Power Distribution / 6. MEDIUM VOLTAGE EQUIPMENT / 6.1 Medium VoltageCircuit Breakers

6.1 Medium Voltage Circuit Breakers

Vaccum- and SF6 circuit breakers are normally installed in the medium voltage power distributionsystems.

Low oil content circuit breakers are still manufactured but are less used due to higher equipment costs.

Figure 6.1.1 Truck mounted vacuum circuit breaker

6.1.2 Truck mounted SF6 circuit breaker

Properties of vacuum- and SF6 circuit breakers

♦ Application:Protection and switching operation for

• lines

• cables

• transformers

• motors



• capacitors

♦ Criterias:

Vacuum SF6

Interrupter service life 20’000 to 30’000C-0 operations

10’000 to 20’000C-O operations

Service interval Lubrication ofmechanism(max. 10years)

Lubrication ofmechanism (max. 10years)

Overhaul of interrupter Interrupter to bereplaced

Interrupter can bereconditioned

Switching of lines,cables, transformers,capacitors

Well suited Well suited

Switching of motors Well suited butmeasures may benecessary to limit overvoltages

Well suited normally nomeasures necessary tolimit over voltages

Engineering / B07 - Eng / C02 - Power Distribution / Power Distribution / 6. MEDIUM VOLTAGE EQUIPMENT / 6.2 Medium VoltageContactors

6.2 Medium Voltage Contactors

The psychical principles are similar to a circuit breaker, except that the contactor cannot interrupt shortcircuit currents. The contact system is optimised for high numbers of rated current operations.

High rupture capacity current limiting fuses in conjunction with the contactor are therefore required forthe short circuit protection.

Overload protection is ensured by separate relays.

Fused contactors can be used as motor and transformer feeders.

Examples for max. fuse rating 250 A, 6 kV:

♦ distribution transformers max. 2000 kVA

♦ motor with max. starting current 1350 A and max. starting time 10 sec. - max. 1690 kW.

Advantages of fused contactors:

♦ very compact design

♦ more economical than circuit breakers

Disadvantages of fused contactors:

♦ tripping mechanism with auxiliary contact required for each fuse

♦ limited application (voltage, current)

♦ fuses to be replace

Figure 6.2 Contactor panel (double tier)



Engineering / B07 - Eng / C02 - Power Distribution / Power Distribution / 6. MEDIUM VOLTAGE EQUIPMENT / 6.3 Medium VoltageTransformers

6.3 Medium Voltage Transformers

These transformers too are normally mineral oil-immersed. For special applications silicone oil is usedwhich has less heat development during fire than mineral oil (10%).

Figure 6.3.1 Oil-immersed three-phase distribution transformer with oil conservator(hermetically sealed transformers without conservator are normally used up to 1000 kVA,resp. up to 20 kV)

So called ‘dry’ transformers which use a synthetic resign as insulation are built up to 10 MVA. They aremore expensive than oil transformers.

Figure 6.3.2 Dry-type three-phase distribution transformer



Engineering / B07 - Eng / C02 - Power Distribution / Power Distribution / 7. LOW VOLTAGE EQUIPMENT

7. LOW VOLTAGE EQUIPMENT

Low voltage switch gear is located in electrical rooms in the different load centres of the plant.

Engineering / B07 - Eng / C02 - Power Distribution / Power Distribution / 7. LOW VOLTAGE EQUIPMENT / 7.1 Motor Control Centres

7.1 Motor Control Centres

The motor control centres comprise all equipment for the remote control of the low voltage consumers(motors etc.). A fuseless and standardised execution of the feeder is preferred.

Figure 7.1 Motor control centre with outgoing feeders of the draw-out, fully-plugged design

Engineering / B07 - Eng / C02 - Power Distribution / Power Distribution / 7. LOW VOLTAGE EQUIPMENT / 7.2 Motor ControlInterface

7.2 Motor Control Interface

The power- and control circuit wiring is normally standardised for each type of feeder.

For maintenance and repair purposes start/stop push buttons and OFF/READY isolator switches arelocated near each individual drive.

The DC-control circuits are connected via multi-core cables to the marshalling rack of the respectiveprocess stations.



Figure 7.2 Typical motor feeder circuit diagram

Legend:

MG. Motor Local Go (Start) DI: Digital Input

MS: Motor Local Stop DO: Digital Output

MU: Motor Local Isolated AI: Analogue Input

MT: Motor Thermal Overload D1: Interface Relay ... VDC

MR: Motor Run C1: Contactor

MK: Motor OK F1: Circuit Breaker

JZ: Motor Power *) Option F2: Thermal Overload Device

MD: Motor Start

Engineering / B07 - Eng / C02 - Power Distribution / Power Distribution / 8. CABLES

8. CABLES

The cable installation is an important part in a cement plant. The investment costs are in the range of10 to 15% of the total costs for electrical equipment.

Types of cables

Power cables for

♦ High voltage (e.g. 110 kV) for incoming feeder from power company

♦ Medium voltage (e.g. 6 kV) for medium voltage power distribution of the plant

♦ Low voltage (e.g. 400 V) for low voltage power distribution of the plant

Control cables for

♦ Low voltage (e.g. 220 V) for control circuits

♦ Extra low voltage (e.g. 24 V=) for process control, instrumentation, communication.

Figure 8.1 Medium voltage power cable (3-core)



Figure 8.2 Low voltage power cable (4-core)

Figure 8.3 Extra low voltage cable (multi-core)

Polyethylene resp. cross-linked polyethylene (XLPE) insulated cables are the most widely installedpower cables today in a cement plant. Ethylene-propylene-rubber (EPR) insulated cables will in futurereplace the PE resp. XLPE-cables.

Copper conductors are preferable to aluminium conductors due to the simpler installation method.

For special applications, cables with flame retardant, non-corrosive sheath material (EVA) can beinstalled.

Dimensioning of cables



Power cables have to be carefully dimensioned in respect of

♦ Current carrying capacity by taking into account

• ambient temperature

• kind of installation (ground, air grouping)

♦ Voltage drop (power loss)

♦ Thermal and dynamic short-circuits strength.

Installation of cables

In cement plants most of the cables are mounted on cable trays inside the buildings, on bridges, inwalk-through cable tunnels or they are installed in pipe systems. Therefore, additional mechanicalprotection by armouring is generally not required.

Engineering / B07 - Eng / C02 - Power Distribution / Power Distribution / 9. POWER FACTOR AND ITS IMPROVEMENT

9. POWER FACTOR AND ITS IMPROVEMENT

Engineering / B07 - Eng / C02 - Power Distribution / Power Distribution / 9. POWER FACTOR AND ITS IMPROVEMENT / 9.1 General

9.1 General

The induction motor is the largest producer of reactive power in a cement plant and shall be used hereas an example.

The induction motor draws two power components from the supplying network, or as shown below,from the generator, i.e.:

♦ the active power is transformed by the motor into mechanical energy

♦ the reactive power is transformed by the motor into magnetic energy; but with every change ofpolarity (with the frequency of the supplying network), the magnetic energy is transformed back toelectrical energy.

in other words, it flows back and forth between the motor and the generator.

It can easily be seen that the reactive power is a burden on the generator and the supplying cables. Itappears as a current like the active current and causes losses in the cables, transformers and in thegenerator.

Figure 9.1.1 Typical power flow in motor circuit



Legend:

S: apparent power kVA

Q: reactive power kVar

W: active power kW

P: mechanical power kW

Figure 9.1.2 Vector diagram

Legend:

OA: Active power W (kW)

OB: Inductive reactive power Q (kVar)

OC: Apparent power S (kVA)

CD: Capacitor reactive power Q (kVar)

Phi: Phase angle, uncompensated

Phi1 Phase angle, compensated

Cos phi: WS

The electricity authorities generally demand a minimum power factor (cos phi) to limit the losses in theirown power distribution system.

One of the most common tools used to improve the power factor is the capacitor. A capacitortransforms reactive power into electrostatic power and back to reactive power with the frequency of thenetwork.

The capacitor can be compared with an expansion tank.

Engineering / B07 - Eng / C02 - Power Distribution / Power Distribution / 9. POWER FACTOR AND ITS IMPROVEMENT / 9.2 Power



Factor Correction

9.2 Power Factor Correction

The plant power factor is normally corrected in three different modes.

♦ For low voltage motors:They can be compensated through automatically regulated reactive current compensation plantssituated at each low voltage power distribution.

Figure 9.2.1 Automatically controlled capacitor bank with line reactors (to cope with theharmonic content)

♦ For high voltage motors with constant speed:To correct the power factor, capacitor banks suitably sized for each individual high voltage motorcan be connected and disconnected from the medium voltage power distribution with the respectivemotor circuit breaker.

Figure 9.2.2 Direct compensated high voltage motor

♦ For large variable speed drives:It is recommended to compensate large variable speed drive systems through central reactivepower compensation plants, correcting the power factor as well as higher harmonics generated bythe various kinds of converters (one plant per medium voltage busbar section).

Prior to the installation of a compensation plant, a detailed network analysis must be carried out.

Figure 9.2.3 Circuit diagram of a harmonic absorber and power factor compensation circuit (1



MVAr)

Legend:

L: Inductance, 14.1 mH

R: Resistor 50 Ω

C1: Capacitor 720 µF

C2: Capacitor 90 µF

PROT: Protection (MCX 912)

Engineering / B07 - Eng / C02 - Power Distribution / Power Distribution / 10. ENERGY- / POWER-METERING

10. ENERGY- / POWER-METERING

The power distribution scheme of a cement plant shall comply with the process requirements.Independent process departments receive independent power supplies and distributions. Therefore,metering equipment shall be installed at:

♦ the H.V. incoming feeder (metering for energy invoice)

♦ the M.V. outgoing feeders to the individual process departments

♦ the M.V. outgoing motor feeders

♦ the L.V. outgoing non-process feeders

♦ the L.V. outgoing main motor feeders

This allows for detailed information such as:

Engineering / B07 - Eng / C02 - Power Distribution / Power Distribution / 10. ENERGY- / POWER-METERING / 10.1 Metering forenergy invoice

10.1 Metering for energy invoice

♦ total active energy consumption (kWh)

♦ total reactive energy consumption (kVarh)

♦ power factor (cos phi)



♦ total power demand (kW)

Engineering / B07 - Eng / C02 - Power Distribution / Power Distribution / 10. ENERGY- / POWER-METERING / 10.2 Metering forinternal use only

10.2 Metering for internal use only

♦ energy consumption per department (kWh)

♦ specific energy consumption per department (kWh/t)

♦ power demand per department (kW)

For a typical arrangement of metering equipment see Fig. 10.2.

Figure 10.2 Energy-/power metering in a cement plant

Engineering / B07 - Eng / C02 - Power Distribution / Power Distribution / 11. SAFETY PRECAUTIONS ON ELECTRICAL EQUIPMENT

11. SAFETY PRECAUTIONS ON ELECTRICAL EQUIPMENT

Engineering / B07 - Eng / C02 - Power Distribution / Power Distribution / 11. SAFETY PRECAUTIONS ON ELECTRICAL EQUIPMENT /11.1 Introduction

11.1 Introduction

The use of electrical equipment, from the main feed down to the hidden auxiliary servo-motor at the farend, spreads potential dangers all around the factory. The application of the safety precautions andregulations is the duty of all employees.

All electrical systems are grounded to earth to reduce the shock hazard to personnel and to provide apath to ground for currents induced in the system by lightning strokes.

Engineering / B07 - Eng / C02 - Power Distribution / Power Distribution / 11. SAFETY PRECAUTIONS ON ELECTRICAL EQUIPMENT /11.2 ‘Touch’ Voltage

11.2 ‘Touch’ Voltage

Figure 11.2 Equivalent circuit of a person exposed to ‘touch’ voltage



Touch voltage is defined as the potential difference between a grounded point and a point on theearth’s surface equal to a person’s normal maximum horizontal reach. Fault current flowing into theearth via the grounded casing of the motor will develop a voltage drop across RE, representing totalground system resistance. A person touching the faulty motor will be safe as long as his bodyresistance RB and his contact resistance to the earth RC are much bigger than RE. The body resistanceRB varies greatly, even on the same person, between approx. 1,300 Ohm on a hot day in a humidatmosphere and approx. 3,000 Ohm in dry weather and with dry hands.

The maximum permissible voltage the body can be exposed to without immediate danger is 65 V. Thiscorresponds under worst conditions to a maximum current of:

These values of 65 V and 0.05 A are laid down in the German VDE regulations. In many countries,however, the voltage considered to be safe is 50 V.

Engineering / B07 - Eng / C02 - Power Distribution / Power Distribution / 11. SAFETY PRECAUTIONS ON ELECTRICAL EQUIPMENT /11.3 ‘Step’ Voltage

11.3 ‘Step’ Voltage

Figure 11.3 Equivalent circuit of a person exposed to ‘step’ voltage

‘Step’ voltage is another hazardous condition caused by distributed voltage gradients. It is defined asthe potential difference between two points on the earth’s surface separated by a distance of aperson’s pace (about 1 m). The figure above illustrates such a condition. Again, fault current flowinginto the earth via the grounded pylon will develop a voltage drop across RE representing the totalground system resistance. Voltage appearing across portion ∆U will determine the magnitude to which



the body will be exposed. Keeping the total ground system resistance low will reduce the value of ∆ Ufor safety purposes.

Engineering / B07 - Eng / C02 - Power Distribution / Power Distribution / 11. SAFETY PRECAUTIONS ON ELECTRICAL EQUIPMENT /11.4 Safety Precautions in High Voltage Equipment Rooms

11.4 Safety Precautions in High Voltage Equipment Rooms

The electrical equipment in the plant has to be protected in such a way that no one can touch any liveparts. National as well as international safety codes have set up strict rules for all equipment, itsinsulation, wiring and earthing.

In electrical rooms, strictly accessible to trained electricians only, different regulations apply which allowfor live parts to be exposed.

Special precautions therefore have to be taken in case of alterations and/or maintenance in suchrooms. Under no circumstances should artisans of other trades (e.g. masons) be allowed to work insuch rooms without the supervisions of an electrician. Temporary barricades may also be required toisolate work areas to prevent accidental contact with energised high voltage parts.

Engineering / B07 - Eng / C02 - Power Distribution / Power Distribution / 11. SAFETY PRECAUTIONS ON ELECTRICAL EQUIPMENT /11.5 Preventive Maintenance

11.5 Preventive Maintenance

Each cement plant has a variety of mobile equipment which is temporarily connected to the power orlight network by means of cord connections. Such flexible connections are subjected to abnormal wear;the electrical staff must, therefore, pay special attention to proper maintenance and repair.

The grounding system has to be measured at regular intervals to assure its low resistance and todetect any faulty or corroded connections.

It is recommended to protect all plug sockets by differential current earth leakage breakers.

In areas where flammable or potentially explosive goods are stored or handled, the electricalinstallations have to be flame-proof or explosion-proof. Such equipment may be necessary withinsections of the oil treatment plant or near natural gas installations.

Engineering / B07 - Eng / C02 - Power Distribution / Power Distribution / 11. SAFETY PRECAUTIONS ON ELECTRICAL EQUIPMENT /11.6 Precautions against Electric Fires

11.6 Precautions against Electric Fires

An American factory insurance company has compiled statistics showing that wiring alone isresponsible for almost half the electric fires, and that over half the losses could have been avoided bycorrecting minor wiring defects.

Sufficient attention is normally paid to the proper protection of oil filled transformers, thus limitingdamage because of fire.

Wiring, however, covers large areas of every structure; it is attached to or part of all types ofmachinery, and is exposed to almost every conceivable environment; heat, cold, dust, moisture, oil,vibration, corrosive liquids and gases. Cables are grouped in large steel enclosures, floor trenches,junction boxes, pits, manholes, and tunnels. Fires in such places are often well-advanced before beingdiscovered. The limited accessibility impedes the application of extinguishing agents.

The almost universal use of PVC-covered and sheathed cables can increase the damage of such firesbecause of the extensive development of fumes of hydrochloric gases which combine to hydrochloric



acid in the presence of moisture.

As a protection against such damages and prevention of plant interruption caused by wiring fires, thefollowing means should be considered:

♦ installation of sprinklers

♦ division of long cable tunnels or trenches into partitions

♦ proper insulation of hot stream or oil pipes using the same tunnel

♦ proper protection against sparks during welding operations

♦ sufficient separation and ventilation of cables subjected to high loads

♦ marking of escape routes in trenches

Engineering / B07 - Eng / C02 - Power Distribution / Power Distribution / 11. SAFETY PRECAUTIONS ON ELECTRICAL EQUIPMENT /11.7 Maintenance of Temporary Installations during Construction and Erection

11.7 Maintenance of Temporary Installations during Construction and Erection

Special attention has to be paid to the proper handling and maintenance of temporary installations.Cables suspended on steel structures are dangerous; if they tear they can set alive the wholestructure. Mobile boom cranes, which can quickly change their working location, are frequently thecause of electrical accidents when they touch overhead lines or tear down suspended cables.

Engineering / B07 - Eng / C02 - Power Distribution / Power Distribution / 11. SAFETY PRECAUTIONS ON ELECTRICAL EQUIPMENT /11.8 First Aid

11.8 First Aid

First aid instruction posters are commonly available and prescribed in electrical rooms.

Since quick and correct action in case of an electrical accident is of vital importance, first aid trainingshould take place at regular intervals.

Engineering / B07 - Eng / C02 - Power Distribution / Power Distribution / 12. ANNEXES

12. ANNEXES

Engineering / B07 - Eng / C02 - Power Distribution / Power Distribution / 12. ANNEXES / 12.1 Power Supply Typical elements of ahigh voltage transformer station

12.1 Power SupplyTypical elements of a high voltage transformer station



Engineering / B07 - Eng / C02 - Power Distribution / Power Distribution / 12. ANNEXES / 12.2 Power Distribution Protective relays

12.2 Power DistributionProtective relays

Engineering / B07 - Eng / C02 - Power Distribution / Power Distribution / 12. ANNEXES / 12.3 Power Distribution Typical elements ofa medium voltage power distribution

12.3 Power DistributionTypical elements of a medium voltage power distribution



Engineering / B07 - Eng / C03 - Drive Systems

C03 - Drive Systems



Engineering / B07 - Eng / C03 - Drive Systems / Drive Systems

Drive SystemsUrs Rüesch

1. INTRODUCTION

2. MOTORS

2.1 Squirrel cage motor (induction motor)

2.2 Slip ring motor

2.3 Synchronous motor

2.4 Synchronous induction motor

2.5 DC motor (direct current motor)

2.6 Ring motor (gearless mill drive)

3. POWER ELECTRONICS

3.1 Introduction

3.2 Operating characteristics of power electronic elements

3.3 Application for power electronics in the cement industry

4. VARIABLE SPEED DRIVE SYSTEM

4.1 Introduction

4.2 Electrical variable speed drive system

4.3 Hydraulic variable speed drive system

5. CRITERIA FOR ASSESSMENT

5.1 Specifications

5.2 Reliability

5.3 Efficiency

6. CONCLUSIONS

7. MESSAGES



Engineering / B07 - Eng / C03 - Drive Systems / Drive Systems / 1. INTRODUCTION

1. INTRODUCTION

The power range of the drives in a cement work is very wide-spread. We normally find motors rangingfrom 0.2 kW up to 6 MW.

Low voltage drives are fed with 380 V to 580 V. For direct feed of drives exceeding 250 kW, thevoltage range of 3.6 kV to 6 kV (11 kV) is used (high voltage motors).

The evaluation criteria of high or low voltage drives are additionally dependent on:

♦ the distance between the motor and the substation (cable costs)

♦ investment costs of the drive(including costs of switching elements).

There is a certain tendency to raise high voltage to 10 KV and the low voltage to 660 V. With highervoltage, service currents and short-circuit currents are reduced, thus a number of advantages areattained, e.g.:

♦ smaller cable cross-sections (lower investment costs)

♦ full advantage can be taken of the 10 kV voltage by the switchgear

♦ low voltage motors can be used up to 500 kW.

Fig. 1: Input/output diagram

The size and thus the investment cost of a motor is not only dependent on the power, but also on thespeed of the motor:

♦ power = torque x speed

To understand the operation of a drive it is very important to know the characteristic “torque vs speed”.

The influence of the torque or speed on the size of a motor can also be explained by means of amechanical example:

♦ truck (30 t payload)motor: 15 l > power = 200 kW

♦ formula 1 racing carmotor: 2 l > power = 400 kW



The truck motor generates a much higher torque at a much lower speed.

The very high degree of efficiency - up to 96% - of electrical drives should be mentioned. In spite ofthis high rate, the warming of large motors due to losses is remarkable.

Thus, ventilation should never be neglected in the planning of electrical drives. Depending on theprevailing conditions, machines can be cooled in different ways:

♦ natural cooling by convection, heat by itself produces an air current

♦ forced cooling by fans and filters

♦ forced cooling by air-to-air or air-to-water heat exchanger (closed-circuit ventilation).

The box-shaped casing makes the motor very versatile as regards its enclosure, so that it can beadapted to suit the wide range of environmental impacts encountered in cement works, most of whichare far from favourable. For example, if a motor has to be installed outdoors, it can be fitted with aweather-proofing attachment. If the attachment is also lined with sound-absorbent material, it actsfurthermore as an excellent silencer.

The type of protection of a motor is very important in the cement industry. The different types ofprotection are characterized by the so-called IP (interelement protection) class, followed by twonumbers which indicate the degree of protection (according to IEC). e.g. IP 44 means:

♦ protection against foreign bodies with a diameter above 1 mm

♦ protection against spray water from all directions.

The cooling of a motor is closely related to its protection. The ideal solution of a completely closed,surface-cooled motor is problematic for big motors. Forced cooling with air filters or air/water heatexchangers are required. Figure 2 shows some examples.

Fig. 2: Various alternatives for air-cooling and protection (for motors bigger than 1 MW)

a) separate ventilation, inlet and outlet through ducting

b) machine fitted with fan and exhaust shroud

c) machine fitted with through-draught ventilation unit with built-in filters



d) machine fitted with air-to-air cooling ventilation unit; the internal and external cooling air circuits arecompletely separate.

Engineering / B07 - Eng / C03 - Drive Systems / Drive Systems / 2. MOTORS

2. MOTORS

Engineering / B07 - Eng / C03 - Drive Systems / Drive Systems / 2. MOTORS / 2.1 Squirrel cage motor (induction motor)

2.1 Squirrel cage motor (induction motor)

Engineering / B07 - Eng / C03 - Drive Systems / Drive Systems / 2. MOTORS / 2.1 Squirrel cage motor (induction motor) / 2.1.1Construction

2.1.1 Construction

The squirrel cage motor is in its construction the simplest motor used in the cement industry. The mainfeature is a rotor without external connections (no slip rings, no brushes). Its two bearings are the onlyparts exposed to wear and tear. It is furthermore economic in price.

Fig. 3: Typical connection diagram of a squirrel cage motor

Fig. 4: Typical starting characteristics of a squirrel cage motor

a : starting torque b : saddle torque

c : break-down torque I : current



c : break-down torque I : current

M : torque n : speed

cosϕ : power factor η : efficiency

P : load

Engineering / B07 - Eng / C03 - Drive Systems / Drive Systems / 2. MOTORS / 2.1 Squirrel cage motor (induction motor) / 2.1.2Operating Characteristics

2.1.2 Operating Characteristics

The squirrel cage motor has a high starting current of 3.5 to 7 times full load at relatively constantspeed.

The torque changes with the square of the voltage.

Fig. 5: Operating characteristics of a squirrel cage motor (abbreviations see Figure 4)

Engineering / B07 - Eng / C03 - Drive Systems / Drive Systems / 2. MOTORS / 2.1 Squirrel cage motor (induction motor) / 2.1.3Application

2.1.3 Application

For almost any drive with a constant speed requirement and not too long a starting time. From afraction of a kW to thousands of KW.

Engineering / B07 - Eng / C03 - Drive Systems / Drive Systems / 2. MOTORS / 2.2 Slip ring motor

2.2 Slip ring motor

Engineering / B07 - Eng / C03 - Drive Systems / Drive Systems / 2. MOTORS / 2.2 Slip ring motor / 2.2.1 Construction

2.2.1 Construction

The slip ring motor, like the squirrel cage motor, is an induction motor.

Its rotor windings are brought out to slip rings which allow to control the starting torque and currentwithin a wide range.

Fig. 6: Typical connection diagram of a slip ring motor



Fig. 7: Start of a slip ring motor by eight steps

MN : nominal torque

MA : torque characteristics during start-up

MG : torque of the load

The introduction of an external resistance in the rotor circuit changes the torque characteristic of themotor and reduces the starting current. It allows changes of the torque of the motor and adaptation tothe torque of the load (e.g. maximum torque at standstill).

The starting time of the motor can be extended since most of the heat is generated in the startingresistor away from the motor.

Metal starting resistors are built in different numbers of steps as required by the drive.

The last step of the resistor may be permanently connected to the rotor when the drive requires asofter torque characteristic.

Liquid starting resistors provide smooth and continuous acceleration.

Engineering / B07 - Eng / C03 - Drive Systems / Drive Systems / 2. MOTORS / 2.2 Slip ring motor / 2.2.2 Operating Characteristics


The slip ring motor is, once started and short-circuited with the resistor, not different from the squirrelcage motor.



Engineering / B07 - Eng / C03 - Drive Systems / Drive Systems / 2. MOTORS / 2.2 Slip ring motor / 2.2.3 Application

2.2.3 Application

Where the starting torque and the starting current must be adjusted to the specific requirements of thedrive. From one to thousands of kW.

Engineering / B07 - Eng / C03 - Drive Systems / Drive Systems / 2. MOTORS / 2.3 Synchronous motor

2.3 Synchronous motor

Engineering / B07 - Eng / C03 - Drive Systems / Drive Systems / 2. MOTORS / 2.3 Synchronous motor / 2.3.1 Construction

2.3.1 Construction

The synchronous motor has a rotor with salient poles. The rotor is connected by slip rings and brushesto a direct current power supply for its excitation.

The AC windings are in the stator. The starting torque of an ideal synchronous motor is zero. Toimprove this situation, the rotors of synchronous motors are normally equipped with a squirrel cagetype winding.

Fig. 8: Typical connection diagram of a synchronous motor

Engineering / B07 - Eng / C03 - Drive Systems / Drive Systems / 2. MOTORS / 2.3 Synchronous motor / 2.3.2 Starting Characteristics

2.3.2 Starting Characteristics

Fig. 9: Typical starting characteristics of a synchronous motor



M : torque

a) Motor with massive poles and starting winding

b) Motor with laminated poles and starting winding

The synchronous motor accelerates, similar to a squirrel cage motor, up to near-synchronous speed.At his point the so far short-circuited DC winding is connected to the rotor. The torque now producedwill accelerate the motor to synchronous speed.

Engineering / B07 - Eng / C03 - Drive Systems / Drive Systems / 2. MOTORS / 2.3 Synchronous motor / 2.3.3 OperatingCharacteristics


The speed of the synchronous motor is proportional with the frequency of the supplying network andindependent of the load on the motor shaft up to the break-down torque. The break-down torque is 1.5to 1.9 times the nominal torque and depends on the excitation.

The great advantage of the synchronous motor is its capability of compensating reactive power and thevery high efficiency of 96 to 98%.

Engineering / B07 - Eng / C03 - Drive Systems / Drive Systems / 2. MOTORS / 2.3 Synchronous motor / 2.3.4 Application

2.3.4 Application

For rather steady loads with no speed control above 500 kW and where reactive power has to becompensated.

Engineering / B07 - Eng / C03 - Drive Systems / Drive Systems / 2. MOTORS / 2.4 Synchronous induction motor

2.4 Synchronous induction motor

The synchronous induction motor combines the advantages of the slip ring motor and the synchronousmotor.

It has the high starting torque at a low starting current of the slip ring motor and also the capability ofcompensating reactive power.

Engineering / B07 - Eng / C03 - Drive Systems / Drive Systems / 2. MOTORS / 2.4 Synchronous induction motor / 2.4.1 Construction

2.4.1 Construction

The synchronous induction motor is built like a slip ring motor; only the mode of operation differs.

Fig. 10: Typical connection diagram of a synchronous induction motor



a) induction motor

b) starting resistor

c) DC power supply

Engineering / B07 - Eng / C03 - Drive Systems / Drive Systems / 2. MOTORS / 2.4 Synchronous induction motor / 2.4.2 StartingCharacteristics

2.4.2 Starting Characteristics

The synchronous induction motor starts with a starting resistor like a slip ring motor. After the starterhas short-circuited the rotor windings, the DC field is applied and the motor accelerates to fullsynchronous speed.

Engineering / B07 - Eng / C03 - Drive Systems / Drive Systems / 2. MOTORS / 2.4 Synchronous induction motor / 2.4.3 OperatingCharacteristics


In the synchronized operating mode the motor acts like a synchronous motor. It can operate with unitypower factor or even compensate reactive power.

Engineering / B07 - Eng / C03 - Drive Systems / Drive Systems / 2. MOTORS / 2.4 Synchronous induction motor / 2.4.4 Application

2.4.4 Application

For rather steady loads with no speed regulation, above 500 kW. Where reactive power has to becompensated and starting torque and current have to be adjusted to the requirements of the drive.

Engineering / B07 - Eng / C03 - Drive Systems / Drive Systems / 2. MOTORS / 2.5 DC motor (direct current motor)

2.5 DC motor (direct current motor)

Its name implies that the DC motor runs on a direct current power supply.

This power supply is not directly available in our cement plant. To connect a DC motor to ourthree-phase alternating current network, an AC-DC converter is required (see para 3. below).

Engineering / B07 - Eng / C03 - Drive Systems / Drive Systems / 2. MOTORS / 2.5 DC motor (direct current motor) / 2.5.1 DC MotorDesign

2.5.1 DC Motor Design



Like all other electric machines, the DC motor consists of a stator and a rotor.

The excitation windings around the main stator poles are fed by a DC power supply and produce aconstant magnetic field.

The DC current in the rotor conductors underneath the main poles produce a tangential force on therotor which is identical to the torque on the motor shaft.

Fig. 11: Magnet flux of a DC motor

Fig. 12: Magnetic forces turning the rotor

The rotor now moves to the neutral position between the south and the north pole.

To keep the armature rotating, a polarity change in the rotor circuit is required. This is achieved withthe collector.

Commutation poles are furthermore installed in the neutral zones between north and south pole. Thesecompensate the remaining magnetic field and thereby improve the commutation.

Fig. 13: DC machine with main and commutation poles



Fig. 14: Cut-away view of a large DC motor

Engineering / B07 - Eng / C03 - Drive Systems / Drive Systems / 2. MOTORS / 2.5 DC motor (direct current motor) / 2.5.2Characteristics of a DC Motor

2.5.2 Characteristics of a DC Motor

The DC motor offers the great advantage of a simple torque and speed control over the full speedrange, as well as high efficiency also for low speeds.

The torque can either be constant over the whole speed range, or any particular speed can bemaintained independent of the torque.

These properties made the DC motor the most commonly used variable speed drive in the cementindustry.

The main drawbacks of the DC drives are that they:

♦ are 2 - 4 times more expensive than squirrel cage motors

♦ are maintenance-intensive (collector, power electronic)

♦ are space-intensive (transformer, converter)

♦ require many spare parts

Engineering / B07 - Eng / C03 - Drive Systems / Drive Systems / 2. MOTORS / 2.5 DC motor (direct current motor) / 2.5.3 Application

2.5.3 Application



DC motors are installed where variable speed is necessary and where the excellent characteristics ofthe drives outweigh the above mentioned drawbacks. Crusher feeders, weigh belt feeders, separators,kiln drives and kiln fans are such possible applications.

Engineering / B07 - Eng / C03 - Drive Systems / Drive Systems / 2. MOTORS / 2.6 Ring motor (gearless mill drive)

2.6 Ring motor (gearless mill drive)

Engineering / B07 - Eng / C03 - Drive Systems / Drive Systems / 2. MOTORS / 2.6 Ring motor (gearless mill drive) / 2.6.1Construction

2.6.1 Construction

The ring motor is a synchronous motor. However, the stator has a variable frequency supply,generated in a frequency converter as described in para 3. below. The frequency ranges between zeroand a few Hertz.

Engineering / B07 - Eng / C03 - Drive Systems / Drive Systems / 2. MOTORS / 2.6 Ring motor (gearless mill drive) / 2.6.2 OperatingCharacteristics


The feature of variable frequency is used to start the motor. The torque can then be adjusted to thetorque of the load resulting in a very smooth starting with low starting currents.

The power factor of the motor itself can be unity, the frequency converter, however, requires somereactive power.

Fig. 15: Starting characteristics of a synchronous motor with frequency and withasynchronous starting

M) torque

n) speed

I) motor current

1) torque of the load (mill)

2) torque with frequency starting

3) current with frequency starting

4) torque with asynchronous starting



5) current with asynchronous starting

Engineering / B07 - Eng / C03 - Drive Systems / Drive Systems / 3. POWER ELECTRONICS

3. POWER ELECTRONICS

Engineering / B07 - Eng / C03 - Drive Systems / Drive Systems / 3. POWER ELECTRONICS / 3.1 Introduction

3.1 Introduction

The recent development of semiconductors has raised the application of power electronics to a level ofconsiderable importance. The capacity/price ratio has become very interesting, and the reliability of theelements is in accordance with the industrial specifications.

To distinguish between electronics and power electronics, it may be said that electronics handlecurrents above 1 mA while power electronics handle currents above 1 A. The present maximum isabout 9000 A (rectifier diodes) for a single element.

The principle elements of power electronics are:

♦ diodes

♦ transistors

♦ thyristors

♦ triacs

♦ GTO (gate turn-off thyristors)

♦ IGBT (insulated gate bipolar transistors)

Other electrical switching elements, such as the conventional thyratron, are not a subject of thisexposé as they are vacuum-tube based and very rarely applied in the cement industry today; butfunctionally, these multi-grid tube elements possess similar operating characteristics.

The above mentioned electronic switches can be compared with other physical media, e.g. valves inwater mains.

Engineering / B07 - Eng / C03 - Drive Systems / Drive Systems / 3. POWER ELECTRONICS / 3.2 Operating characteristics of powerelectronic elements

3.2 Operating characteristics of power electronic elements

Engineering / B07 - Eng / C03 - Drive Systems / Drive Systems / 3. POWER ELECTRONICS / 3.2 Operating characteristics of powerelectronic elements / 3.2.1 Diode

3.2.1 Diode

The symbol for a diode is shown in Figure 16 below. The operating characteristics of this element arevery easy to understand. If a voltage "U1" is applied across the diode from anode A to cathode C, thea current "i" will flow through the diode. If the voltage "U2" is reversed from C to A, the diode blocks thecurrent, i.e. no current will flow.

Figure 17 demonstrates the "rectifying effect" of a diode.

Fig. 16: Symbol for a diode



Fig. 17: "Rectifying effect" of a diode (half-ware rectifier)

The voltage "U" changes its polarity with every cycle. When the voltage across the diode is "positive" acurrent "i" flows through the load "L".

Figure 18 below shows a more efficient network.

Fig. 18: Full-wave rectifier

The current "i" is conducted alternatively by the two diodes. The time phase when the one "passes" thecurrent to the other is called commutation.

Engineering / B07 - Eng / C03 - Drive Systems / Drive Systems / 3. POWER ELECTRONICS / 3.2 Operating characteristics of powerelectronic elements / 3.2.2 Transistor



3.2.2 Transistor

The transistor is built with three semi-conducting materials similar to a diode, which has two.Depending on the physical arrangement of these three semi-conducting materials, the literature speaksof PNP or NPN transistors. Also, the symbol and electrical circuitry is different, but today generally thePNP concept is manufactured.

The transistor can be used in many different circuit-configurations, but is basically a current amplifier,whereas the old electron tubes where voltage amplifiers.

Fig. 19: Symbols and typical transistor circuits

è small current controlling the transistor (closed or conducting)

è large current through the load

(note: arrows do not indicate the electron-flow)

The transistor input current (base-emitter) controls the transistor output current (emitter-collector) in aproportional manner over a certain range. Of course, the same transistor may also be used asswitching element only, i.e. fully closed and fully conducting. Above is identically valid for PNP andNPN types.

Elements with output currents above 1 A are called power transistors, used as last stage in amplifiersand variable frequency converters for smaller drives up to approx. 400 kW.

Engineering / B07 - Eng / C03 - Drive Systems / Drive Systems / 3. POWER ELECTRONICS / 3.2 Operating characteristics of powerelectronic elements / 3.2.3 Thyristor, Triac

3.2.3 Thyristor, Triac

The symbol for a thyristor is shown in Figure 20. The operating characteristics of this element aresimilar to those of a diode except for the additional ignition voltage "Ug" from point anode A to pointgate G.

Fig. 20: Thyristor symbol



If a voltage "U1" is applied across the thyristor, current "i" will only flow through the element when avoltage "Ug" (ignition voltage) is applied between A and G. The current "i" will flow only as long as thevoltage "U1" does not change its polarity.

The network in Figure 21 demonstrates the use of thyristors as a voltage regulator for DC.

Fig. 21: Network for a variable DC supply

By altering the angle of ignition, α, one can alter their voltage "U" across the load "L", theoreticallywithin the range 0 - 100%.

The symbol for a triac is shown in Figure 22 below. A triac consists of two antiparallel thyristors. Thiselement represents an electronic switch for alternating current.

Fig. 22: Symbol for a triac.



A1 = anode 1

A2 = anode 2

Ug = ignition voltage

Together with the ignition voltage "Ug", the triac is able to conduct the current in both directions.

Figure 23 below shows its application as a "voltage" regulator" for an AC-load.

Fig. 23: The triac as “voltage regulator” for an AC-load

Engineering / B07 - Eng / C03 - Drive Systems / Drive Systems / 3. POWER ELECTRONICS / 3.2 Operating characteristics of powerelectronic elements / 3.2.4 GTO (Gate turn-off-thyristor)

3.2.4 GTO (Gate turn-off-thyristor)

The symbol for a GTO is shown in Figure 24 below. The special feature of the GTO's is that they arenot only turned on through their gate, but also off. Naturally, this would be the ideal switch, because noforced commutation equipment would then be needed to turn off the current when the thyristor isoperated on direct voltage. In order to turn off the thyristor through the gate, negative triggering pulseswhich are large enough to reduce the load current of the thyristor below the holding current for a brieftime are required. The turn-off pulse must be at least 10% of the forward current.

Fig. 24: Symbol for a GTO

Figure 25 shows a pill of silicon with multitude of small, circular arranged "cathode-fingers" which arelooking out of a connected gate-surface. Each "finger" is an independent small GTO. All these small



GTO's are connected in parallel to a large GTO.

Fig. 25: Pill of silicon

Gate turn-off thyristors are used for forced-commutated current converters and static inverters.

Engineering / B07 - Eng / C03 - Drive Systems / Drive Systems / 3. POWER ELECTRONICS / 3.2 Operating characteristics of powerelectronic elements / 3.2.5 IGBT (Insulated gate bipolar transistor)

3.2.5 IGBT (Insulated gate bipolar transistor)

The IGBT is a combination of the advantageous characteristics of a bipolar transistor and aself-blocking field effect transistor (MOSFET). Its characteristics are a powerless drive like a MOSFET,a low forward resistance and a high inverse voltage like a bipolar transistor. Figure 26 shows theequivalent network and figure 27 the symbol for an IGBT.

Fig. 26: Equivalent network for an IGBT

Fig. 27: Symbol for an IGBT



The IGBT is suitable for numerous applications in power electronics, especially in pulse widthmodulated servo and three-phase drives requiring high dynamic range control and low noise. They alsocan be used for power-supplies and other power circuits requiring high switch repetition rates.

IGBT’s will replace the bipolar darlington-transistor in many applications because the control circuit isless sophisticated and thus cost-efficient.

Engineering / B07 - Eng / C03 - Drive Systems / Drive Systems / 3. POWER ELECTRONICS / 3.2 Operating characteristics of powerelectronic elements / 3.2.6 Application for power electronic elements

3.2.6 Application for power electronic elements

Figures 28, 29 and 30 illustrate how a frequency converter can be built with the aid of power electroniccomponents.

Fig. 28: 3-pulse anti-parallel circuit

___ load current

----- circulating current (during transfer motoring to regenerating)

Fig. 29: 6-pulse anti-parallel circuit



___ load current

----- circulating current (during transfer motoring to regenerating)

Figure 30 shows a mounting diagram and voltage from an output phase of a frequency converter. Eachoutput phase is formed by a 6-pulse anti-parallel partial-current converter. Totally at least, 3x2-6(3-phase; 2-anti-parallel; 6-pulse) = 36 current converters are needed. The two partial-currentconverters change between rectifier - and inverter service; so that the output-voltage will be sineshaped.

Fig. 30: Example for a frequency conversion with a time-dependent ignition control

Engineering / B07 - Eng / C03 - Drive Systems / Drive Systems / 3. POWER ELECTRONICS / 3.3 Application for power electronics inthe cement industry

3.3 Application for power electronics in the cement industry

In modern cement works power electronics are used as:

(a) rectifiers for - electrostatic filters- magnetic separators- DC power sources

(b) voltage regulators for - speed (torque) control of DC drives- voltage control of electrostatic filters- electronic contactors



- electronic contactors

(c) frequency converters for - speed control of synchronous motors,e.g. ring motor, squirrel cage motors

- stabilized power sources for supply ofcontrol equipment, e.g. computers

Engineering / B07 - Eng / C03 - Drive Systems / Drive Systems / 3. POWER ELECTRONICS / 3.3 Application for power electronics inthe cement industry / 3.3.1 Advantages of electronic elements

3.3.1 Advantages of electronic elements

Electronic elements do not wear out. Their modular design permits quick trouble-shooting and shortrepair times. Furthermore, they offer ideal characteristics for motor controlling, e.g. speed variation.

Engineering / B07 - Eng / C03 - Drive Systems / Drive Systems / 3. POWER ELECTRONICS / 3.3 Application for power electronics inthe cement industry / 3.3.2 Disadvantages of electronic elements

3.3.2 Disadvantages of electronic elements

a) CoolingEnergy losses occur in electronic elements as they are not ideal switches. These losses produceheat and since the switching components have small dimensions, cooling is a considerableproblem. The cooling media is usually air, but water may also be used (e.g. water-cooled thyristorsof the ring motor at Rekingen). The ambient temperature of electronic boards is often specified upto a maximum of 45oC, thus in most cases air-conditioned rooms are necessary.

b) Distortion of the sine wave formThe above diagrams (e.g. Fig. 30) show that the power electronics "cut" the source sine-wave insuch a way that "angles" are formed. The degree of distortion of the initial wave form represents aquantity of reactive power of higher frequency produced by the power electronics (harmonics).This high frequency power causes the following inconveniences:

• emission of strong magnetic fields which can disturb control signals (control cables must beprotected and separated)

• malfunction of other electrical equipment inside and outside the plant due to distortion of thevoltage wave form.

Summary of semiconductor elements for power electronics

Symbole Description max. voltage &current

DIODES

Diodes ore semi-conductor devices which allow current to flow in onepreferred direction. If o positive voltage is applied, the diode operatesin the forward direction; when the voltage is negative, it blocks. Theproperties of a good diode are high reverse resistance, low forwardresistance and high allowable temperature.

Standard and avalanche diodes are used mainly for rectification incircuits operating ot mains frequency Fost recovery diodes ore usedfor static frequency changers or in pulsed power supply units.

Revers voltage:

100 V ... 30 kV

max. permissible RMSon-state current:

1A ...9000 A



for static frequency changers or in pulsed power supply units.

POWER-TRANSISTOR (Power field effect tranistor)

The silicon pellet of the bipolar power transistor consists of threelayers of alternate p and n type silicon material with two pen¡unctions. On principle the succession of the layers npn or pnp ispossible but today only the pnp concept is manufactured to achieveoptimum electrical characteristics for power electronics.

Power transistors are almost exclusively fumed on and off in"Switching operation". To allow the output current to flow, a forwardbase current must be maintained for the desired duration of theconducting state. When removing the control signal the powertransistor reverts to the blocking state.

max. collector - emittervoltage:

100 V ... 1400 V

max. DC collectorcurrent:

20 A... 400 A

POWER-MOSFET

The Power-MOSFET is a controllable switch, if it is running in forwarddirections. In this case the MOSFET can block up high invers voltageand can switch high power. In backward running it has similarqualities like a diode, but it is possible to influence the characteristiccurve with the tension on the gate. The MOSFET has on advantageover the bipolar transistor because no control current is necessary.

The Power-MOSFET are used for rectifier for DC-motors, frequencyconverter for AC-motors and power supply units.

Break-through voltage

50 V... 1000 V

Output current:

2 A... 100 A

THYRISTOR

The silicon pellet of the thyristor consists of four or more foyers ofalternate p and n type materials. It has two different conditions, one ishigh-resistance and the other one is law-resistance. The differencebetween a diode and a thyristor is, that a thyristor can switch betweenthe two conditions with a current at the gate. To switch off the current,the thyristor needs a quenching capacitor. Thyristors ore used forcontactless switches and controlled rectifiers.

Reverse voltage:

100 V... 5000 V

max. permissible RMSon-state current:

10 A ... 5500 A

GTO (Gate turn-off Thyristor)

The special feature of the GTO is that they are not only turned onthrough their gate, but also off. Naturally, this would be the idealswitch, because no forced commutation equipment would then beneeded to turn off the current when the thyristor is operated on directvoltage. The turn-off pulse has to be about 10% of the forwardcurrent. Gate turn-off thyristors are used for current converters andstatic inverters.

Reverse voltage:

100 V ... 4500 V

max. current:

10 A ... 3000 A

IGBT (Insulated Gate Bipolar Transistor)

The IGBT is o technologically combined device having theadvantageous characteristics of a bipolar power transistor and aself-blocking field effect transistor. This characteristic is thereforesimilar to the MOSFET in the input and to the bipolar power transistorin the output.

The IGBT is suitable for numerous applications in power electronics,especially in Pulse Width Modulated frequency converters andthree-phase drives.

max. collector - emittervoltage:

100 V ... 1200 V

max. DC collectorcurrent:

15 A ... 400 A

Engineering / B07 - Eng / C03 - Drive Systems / Drive Systems / 4. VARIABLE SPEED DRIVE SYSTEM

4. VARIABLE SPEED DRIVE SYSTEM

Engineering / B07 - Eng / C03 - Drive Systems / Drive Systems / 4. VARIABLE SPEED DRIVE SYSTEM / 4.1 Introduction

4.1 Introduction

The correct air volume for the process is often achieved by damper control or radial vanes inconjunction with constant speed drives. Considering the "BCM" (Better Cost Management) concept,constant speed and damper control for large fans (1-4 MW) is forbidden today.



Figure 31 compares the reduced energy consumption of using variable speed equipment for fans andpumps with radial vane damper and throttle valve. Where air or water quantities have to be adjustedaccording to process parameters, a variable flow is needed. Very often, this variable flow is createdwith more losses than necessary. Compared with other means of flow-adjusting devices, the variablespeed drive can save a considerable amount of energy, especially at 50 to 90% of the rated speed.

Fig. 31: Power requirement at different speed

Traditionally, requirements for variable speed in the cement industry were covered with the applicationof direct current (DC) drives or occasionally by hydraulic drive systems.

As a result of new semiconductor developments in the field of power electronics, many static convertercircuits have become reality in recent years. In addition to the traditional DC drive, these staticconverters have opened up new applications for variable-speed AC drives of high ratings.

This paper presents a number of systems, showing where they can be applied and quoting the criteriawhich simplify a choice from the wide variety offered.

Some outstanding advantages of a variable-speed drive as follows:

a) Optimal process control

b) Reduced stress on machines and supply system during starting

c) Better utilization of the primary energy owing to the higher efficiency

Familiarity with the entire spectrum of electrical and mechanical variable speed drive systems is notonly useful when ordering a new plant, but is equally necessary when carrying out partialmodernizations or conversions, e.g. replacing an installation involving undue maintenance or with apoor efficiency.

The following catchwords applies for drive specification:

Robust The drive system must be designed to cope with thetypical cement plant environment and the type andquantity of dust prevailing at the location of installation,e.g. clinker dust for cooler fan drives.



e.g. clinker dust for cooler fan drives.

Ease of maintenance The necessary amount of man-hours required by theequipment must be minimal. Diagnostic systems must helpto identify failures and indicate steps to correct thefault/failure. Modular design and access must allow for afast replacement of the defective component in order torestore normal operation.

Reliability High reliability shall be achieved with adequate sizing of awell-proven drive system. The system shall not beoverengineered with additional redundant equipment,which increases the initial installation cost.

Efficiency Total drive system efficiency is of utmost importance, sinceit will substantially influence the operating cost for manyyears to come at an always increasing cost of electricalenergy

Investment cost Last but not least, also the investment cost shall beconsidered. However, an evaluation oft the investmentcost is only meaningful if complete systems are comparedincluding auxiliary installations (e.g. differences in coolingsystems, civil works etc.) as well as the operating costover the next ten to fifteen years.

Engineering / B07 - Eng / C03 - Drive Systems / Drive Systems / 4. VARIABLE SPEED DRIVE SYSTEM / 4.2 Electrical variable speeddrive system

4.2 Electrical variable speed drive system

Engineering / B07 - Eng / C03 - Drive Systems / Drive Systems / 4. VARIABLE SPEED DRIVE SYSTEM / 4.2 Electrical variable speeddrive system / 4.2.1 DC drive

4.2.1 DC drive

Fig. 32: DC drive system

A DC drive system normally includes:

♦ 3-phase isolation transformer (1)



♦ 3-phase full wave rectifier (2)

♦ DC motor (3) with shuntfield (4) and tachometer (5)

♦ electronic speed regulator (6)

The speed of the DC machine varies proportionally to the applied armature voltage. Motor fieldweakening can increase the speed even more, but the result is reduced torque. DC drives can be builtfrom less than 1 kW to approx. 1000 kW, considering motor speeds of 3000 min-1 for the smaller typeand 700 min-1 for the larger sizes. At steel mills, large DC drive systems are built up to 8 MW withapprox. 100 min-1. The motor size is the limiting factor due to the centrifugal forces of the commutator.The usable speed range is almost infinite, since the DC drive can start and run close to zero speedeven under severe overload conditions. Due to the wide speed range, DC drives in most cases requireexternal forced-cooling systems.

Engineering / B07 - Eng / C03 - Drive Systems / Drive Systems / 4. VARIABLE SPEED DRIVE SYSTEM / 4.2 Electrical variable speeddrive system / 4.2.1 DC drive / 4.2.1.1 Operating Characteristics

4.2.1.1 Operating Characteristics

The scheme as shown in Figure 33 can operate only in quadrant 1, i.e. motoring in forward direction.For full 4-quadrant operation, a double anti-parallel (back-to-back) thyristor bridge arrangement isnecessary.

Once the DC motor is equipped with a forced-cooling system, no torque limitations exist. Totally closedDC machines are available too, but they are oversized and cover a limited speed range only.Therefore, a totally enclosed fan-cooled machine is usually very uneconomical. The field weakeningrange is not used in the cement industry, since it serves mostly for winder applications.

Fig. 33: 4-quadrant operation

Engineering / B07 - Eng / C03 - Drive Systems / Drive Systems / 4. VARIABLE SPEED DRIVE SYSTEM / 4.2 Electrical variable speeddrive system / 4.2.1 DC drive / 4.2.1.2 Application

4.2.1.2 Application

The DC drive system is widely used in the cement industry for the following machines:

♦ kiln main drives ♦ 200 - 500 kW and twin drive

♦ large fans (e.g. kiln, raw mill) ♦ 800 - 2000 kW

♦ weigh feeders ♦ 5 - 15 kW



♦ weigh feeders ♦ 5 - 15 kW

♦ apron feeders and special belt conveyors ♦ 20 - 100 kW

Due to the rapid developments in power electronics, the variable speed drive technology has gonethrough various stages in the last decades, but the DC drive represents still an efficient, approved andeconomic solution today. The commutator, the most delicate part of the whole system, and the coolingsystem require special and permanent maintenance attention. These two aspects explain the desire forother variable speed drive systems without commutator.

Fig. 34: Typical schematic diagram of a twin drive for a rotary kiln employingthyristor-controlled DC motor

1 Rectifier transformer 7 Current controller

2 Reactor 8 Speed controller

3 Thyristor rectifier, controllable 9 Speed reference potentiometer

4 DC motor 10 Current transformer and rectifierfor the current actual value

5 Tacho generator 11 Thyristor rectifier, uncontrollable

6 Gate control unit

Engineering / B07 - Eng / C03 - Drive Systems / Drive Systems / 4. VARIABLE SPEED DRIVE SYSTEM / 4.2 Electrical variable speeddrive system / 4.2.2 AC drive with squirrel cage motor

4.2.2 AC drive with squirrel cage motor

The variable speed drive system, using a squirrel cage motor, consists of the following maincomponents (see Fig. 35):

♦ 3-phase full-wave rectifier (1)

♦ DC-intermediate link with reactors (2)

♦ forced commutated inverter (3)

♦ normal 3-phase squirrel cage motor (4)

An input rectifier creates the intermediate link DC voltage. The reactors inserted in the DC link



uncouple the AC power supply side from the inverter side driving the asynchronous motor. The forcedcommutated inverter is using the principle of phase sequence turn-off. Each of these switching circuitsconsists of a thyristor, a diode and a commutating capacitor. The input rectifier is current-regulated andsupplies its power into the DC intermediate link. The output inverter is voltage regulated, maintainingthe correct V/Hz relationship over the speed range. The speed of the motor is adjusted by variablefrequency. No tachometer is needed, since the frequency feed-back signal is taken from inside thepanel. The normal speed range is from 5 to 50/60 Hz and up to approx. 90 Hz.

The power of the available units presently ranges from 5 kW to approx. 1800 kW of several typical ACinput voltage levels like 380, 415, 500, 660 V AC. In special cases, units of 3 MW have been built forall motor speeds up to 4000 min-1.

Engineering / B07 - Eng / C03 - Drive Systems / Drive Systems / 4. VARIABLE SPEED DRIVE SYSTEM / 4.2 Electrical variable speeddrive system / 4.2.2 AC drive with squirrel cage motor / 4.2.2.1 Current-source inverter-fed induction motor

4.2.2.1 Current-source inverter-fed induction motor

Fig. 35: Frequency converter with phase-sequence turn-off

Operating Characteristics

The converter as described above does not need any additional semiconductors in order to perform afull 4-quadrant operation. The flow of energy is reversed by reversing the polarity of the DC linkvoltage, with the current direction remaining unaltered. At speeds below 5 Hz, torque pulsation may benoted as a result of low frequency motor-current harmonics. This effect is damped by the mass of themechanical system.

The prevailing use for this type of variable speed drive is to be found with fans and pumps in manydifferent configurations.

Usually a totally enclosed, fan-cooled standard motor can be chosen with no extra forced coolingsystem because the torque curve of these mechanical devises follows a square function versus speed.

Fig. 36: Typical block diagram of the voltage-controlled variable frequency converter



1 voltage controller 5 trigger unit of theline-commutated converter

2 value generator and limiter 6 actual current measurement

3 actual voltage measurement 7 voltage/frequency converter

4 current controller (secondary) 8 trigger unit of theself-commutated converter

9 voltage reference potentiometer

Fig. 37: Torque/speed diagram

A : continuous duty self-ventilated

B : continuous duty with forced ventilation

C : intermittent duty

Application

Cooling equipment manufacturers and suppliers of water pumping stations have used this type ofvariable speed drive since 1975. Several converter manufacturers have application references for morethan 1000 units of a wide power range within the past years.

The initial equipment cost is slightly higher than for a comparable DC drive system due to moresemiconductor elements in the power path. On the other hand, the squirrel cage motor is much



cheaper than the DC motor. Harmonic content and power factor aspects are identical with those of aDC drive since the input rectifier represents the same type of load to the supply side network.

This system offers interesting aspects for modifications of existing equipment. When introducing thevariable frequency converter to an installation which was so far connected to a constant 50 or 60 Hzsupply, the motor can be speed-controlled. It might be of interest that even a speed-increase ispossible by applying more than line frequency (e.g. 70 - 90 Hz). In other words, a belt conveyor can runfaster and develop more power without motor - or gear change!

Engineering / B07 - Eng / C03 - Drive Systems / Drive Systems / 4. VARIABLE SPEED DRIVE SYSTEM / 4.2 Electrical variable speeddrive system / 4.2.2 AC drive with squirrel cage motor / 4.2.2.2 Load commutated inverter-fed induction motor

4.2.2.2 Load commutated inverter-fed induction motor

The main components of this drive type consist also of a line-side converter, DC link circuit reactor andload-side converter. Additionally, a so called diverter is added in order to force commutate (switch-off)the inverter at low frequencies, while an output filter is added to smooth output waveforms and provideexcitations for the induction motor.

Fig. 38: Cage induction motor with load-commutated inverter (output Filter)

As with the conventional frequency converters, for normal operation the converter is commutated byline-voltage and the inverter is commutated by the load. Unlike the conventional type, the divertercircuit on the DC link is used to commutate the inverter bridge for low frequency operation. The entireinverter is commutated by the diverter, then appropriate thyristors are gated (switched on) to producethe three-phase output. Above about 60% of rated frequency, depending on the motor, the divertercircuit turns off and the inverter is load commutated by the combined effects of the output filter and theinduced motor-voltage of the induction motor itself. The filter is sized to provide motor excitation over awide frequency range. The voltage and current waveshapes are nearly sinusoidal, typically containingless than 5% harmonic distortion at rated output. No motor derating is necessary.




Application

The load-commutated inverter-fed induction motor is best suitable for loads with squared torque/speedcharacteristic (Fig. 39) and reduced speed range, i.e. for fans.

Engineering / B07 - Eng / C03 - Drive Systems / Drive Systems / 4. VARIABLE SPEED DRIVE SYSTEM / 4.2 Electrical variable speeddrive system / 4.2.3 AC drive with slip ring motor

4.2.3 AC drive with slip ring motor

Fig. 40: Schematic of sub-synchronous cascade

a) HV slip ring motor with tachometer (T)

b) 3-phase full-wave rectifier (diodes)

c) 3-phase full-wave inverter (thyristors)

d) matching transformer

e) electronic speed regulator

f) starting resistor

g) speed reference potentiometer

The stator of the slip ring motor is connected directly to the power system. The rotor slip power, whichis proportional to the slip frequency, is fed back into the power system via a diode rectifier, a smoothingreactor, an inverter and a matching transformer. A starting resistor is normally used to drive the motorup to approx. half speed, then the rotor is connected to the converter and the electronic regulator takesover the speed control. The static converter section has to be sized only for the rotor slip power. The



sub-synchronous cascade system is mostly used to drive large pumps, fans and compressors, wherethe torque increases with the square of the speed. A considerable change in capacity is obtained byonly a slight adjustment in speed, therefore, a large speed range is normally not required. A range of2:1 or 3:1 is more than sufficient.

The normal power range for sub-synchronous cascade systems used in industry is from about 500 kWto 10 MW with motor nominal speeds of 1500 min-1 or below. For special applications, similar convertersystems have been built up to 60 MW. Motor cooling systems are identical to those of normal slip ringmotors running at a constant speed.

Operating Characteristics

A sub-synchronous cascade drive needs a starting resistor. The variable speed range is very muchreduced compared to a DC drive. No oversynchronous speed can be reached and only 1-quadrantoperation is possible, i.e. motoring in one direction only.

Every converter requires reactive power. A larger drive systems has a higher demand for reactivepower, which has to be considered and compensated. With the sub-synchronous cascade drivesystem, the reactive power demand increases with increasing speed range. Therefore, the variablespeed range should be kept as small as possible. The compensation system has to be designed on anindividual basis and should be optimized for the normal running speeds of the motor. Furthermore, theharmonic currents, created by the static converter, have to be considered during the design of thepower factor compensation system. In a modern installation, the filter-circuits cover both aspects,resulting in a combination network of reactors and capacitors instead of capacitors only.

The efficiency of the total variable speed drive system is not as high as that of a slip ring motor alonedue to more power components being involved in the former. The overall efficiency over the speedrange is, however, much better than for example controlling the air-flow with a radial vane damper atconstant motor speed or at variable slip ring motor speed using permanently connected resistances inthe rotor circuit.

Fig. 41: Typical speed/efficiency curve of a sub-synchronous cascade drive

Application

Especially large plants require large fans where DC drives are not feasible as the power/speed ratioexceeds the typical DC motor frame size. Here, the sub-synchronous cascade system offers aninteresting alternative.

A 2000 t/d plant, for example, needs a kiln fan of 1700 kW at 1500 min-1. Large fans in the cementindustry can have a range of up to 5 MW. Therefore, this type of drive will be seen in our industry moreoften since it meets all requirements in terms of controlability, operating behaviour and economy.



Furthermore, any existing slip ring motor can be converted into a variable speed drive by adding asub-synchronous cascade converter system. On the other hand, every cascade system can run atrated motor speed without the static converter, e.g. during a fault in the electronic regulation part.Leaving the mechanical flow control device installed will be of advantage!

The sub-synchronous cascade drive is, therefore, a technically and economically favourable system forlarge fans requiring variable speed du to process parameters.

Engineering / B07 - Eng / C03 - Drive Systems / Drive Systems / 4. VARIABLE SPEED DRIVE SYSTEM / 4.2 Electrical variable speeddrive system / 4.2.4 AC drive with synchronous motor

4.2.4 AC drive with synchronous motor

Engineering / B07 - Eng / C03 - Drive Systems / Drive Systems / 4. VARIABLE SPEED DRIVE SYSTEM / 4.2 Electrical variable speeddrive system / 4.2.4 AC drive with synchronous motor / 4.2.4.1 Synchronous motor with cyclo-converter

4.2.4.1 Synchronous motor with cyclo-converter

Fig. 42: Converter schematic used in conjunction with the ring motor (gearless mill drive)

1) converter transformer

2) two converters in anti-parallel three-phase bridge connection

3) synchronous motor

4) exciter winding

Each motor phase is connected to the feeding power system via two static converters arranged in ananti-parallel three-phase bridge network. A low frequency output voltage is delivered by the convertersby means of phase angle control. At a system frequency of 50 Hz, the maximum attainable outputfrequency is approx. 20 Hz. With this drive system, four-quadrant operation, i.e. reversal of thedirection of rotation and regenerative braking, is possible without any modification. This systemcorresponds fully to a four-quadrant DC drive. A high starting torque and almost sinusoidal currentresults in particularly favourable characteristics at low speeds.

This system is well-suited for the substitution of large DC drives, e.g. for conveying machinery, inrolling mills or as propeller drives for ice breakers and mine winders, especially when the DC motor canno longer be employed because of ambient conditions, maintenance costs or power limits.

The system covers a range from 1 to 20 MW.

Engineering / B07 - Eng / C03 - Drive Systems / Drive Systems / 4. VARIABLE SPEED DRIVE SYSTEM / 4.2 Electrical variable speeddrive system / 4.2.4 AC drive with synchronous motor / 4.2.4.1 Synchronous motor with cyclo-converter / 4.2.4.1.1 Application



4.2.4.1.1 Application

The cement industry uses this system only for large (cement) mills, avoiding the gear and, therefore,saving space and building cost. Of course, this is not of equal importance all over the world and itstechnical complexity can be a drawback in many third world countries. Therefore, this drive system isnot very often selected. But in other industries, it will replace in the near future more often the large DCmachines in the MW-range.

Engineering / B07 - Eng / C03 - Drive Systems / Drive Systems / 4. VARIABLE SPEED DRIVE SYSTEM / 4.2 Electrical variable speeddrive system / 4.2.4 AC drive with synchronous motor / 4.2.4.2 Synchronous motor with intermediate circuit converter

4.2.4.2 Synchronous motor with intermediate circuit converter

Fig. 43: Basic circuit, 6-pulse

Fig. 44: Basic circuit “12-pulse”

Rectifier and inverter, “12-pulse” with two motor windings displaced by 30o el.

Static converter in parallel connection

The circuit is generally called a converter-fed synchronous motor and consists of a controllablerectifier, a smoothing reactor and an inverter. In these designs (Figures 43 and 44 above), rectifier andinverter have to be sized for the full motor power, compared to the sub-synchronous cascade, wherethe converter has to cope with the rotor slip power only. The commutation from one phase to anotherof the inverter is dictated by the terminal voltage of the synchronous machine. This naturalcommutation does not need any additional circuit like e.g. the forced commutation with the convertertype for squirrel cage motors.



This type of converter is suitable for 4-quadrant operation and can cover a full speed range like a DCdrive variable speed system.

The 6-pulse scheme is normally used for power of 1 to 5 MW. For larger systems, the harmoniccurrents lead towards 12-pulse configurations due to motor and line side problems. Modernsynchronous motor drives have a brushless excitation system. An auxiliary asynchronous machine,integrated into the synchronous motor, supplies its power through a rotating diode rectifier to the DCfield winding thus avoiding trouble causing slip rings.

Converter frequencies of up to 120 Hz can be realized driving a two pole synchronous motor up to6000 min-1 at almost any power. Systems of 30 MW have been built and projects of 50 MW are beingstudied.

Engineering / B07 - Eng / C03 - Drive Systems / Drive Systems / 4. VARIABLE SPEED DRIVE SYSTEM / 4.2 Electrical variable speeddrive system / 4.2.4 AC drive with synchronous motor / 4.2.4.2 Synchronous motor with intermediate circuit converter / 4.2.4.2.1Application

4.2.4.2.1 Application

The main applications of the converter-fed synchronous motor for pumps, extruders and compressors,where a precise speed control over a wide speed range is important.

These drives are not installed in the cement industry, as the existing type of machinery does notspecifically require a converter-fed synchronous motor system.

Engineering / B07 - Eng / C03 - Drive Systems / Drive Systems / 4. VARIABLE SPEED DRIVE SYSTEM / 4.2 Electrical variable speeddrive system / 4.2.5 Electronic smooth-start for three-phase motors (soft starters)

4.2.5 Electronic smooth-start for three-phase motors (soft starters)

The simplest and cheapest way to start a three-phase motor is full-voltage, across the line starting, andthat method should be used whenever feasible. But there has always been a need in some applicationsto limit the locked-rotor inrush current to the motor, control motor starting torque, or both.

Control of starting torque and acceleration is often required to protect the dirven-load. For example, itmight be necessary to control acceleration and starting torque of a conveyor motor to prevent shockdamage to system elements and damage to products on the conveyor.

Fig. 45: Electronic soft-start for a three-phase motor

Figure 46 shows the course of torque with a smooth-start for a three-phase motor. The startingprocedure begins by 20 to 40% of the nominal voltage. During the adjusted starting time, the statorvoltage will be increased to 100% through the control of the firing-angle of the thyristor-controllers.



The motor runs up along the load characteristic Ml, whereby torque-shocks will be avoided. The speedincreases linear during the starting time from 0 to the nominal speed of the motor. After the startingprocedure, when the motor runs with nominal load, the thyristor will be fully conducted.

The electronic smooth-start works similar to the hydrodynamic coupling (see chapter 4.3.3), but it hasthe decisive advantage that the starting time and the starting torque can be easier adjusted to theindividual operating conditions.


Summary of large variable speed drive systems for the cement industry (>1 MW)

Engineering / B07 - Eng / C03 - Drive Systems / Drive Systems / 4. VARIABLE SPEED DRIVE SYSTEM / 4.3 Hydraulic variable speeddrive system

4.3 Hydraulic variable speed drive system

Engineering / B07 - Eng / C03 - Drive Systems / Drive Systems / 4. VARIABLE SPEED DRIVE SYSTEM / 4.3 Hydraulic variable speeddrive system / 4.3.1 Hydrostatic drives

4.3.1 Hydrostatic drives

Fig. 47: Scheme of a hydrostatic motor



The hydrostatic motor is connected to a hydraulic high pressure pump system. The oil feed and drainpipes are located on the opposite side of the drive shaft.

The unit can be subdivided into two parts i.e. the drive shaft bearing part and the torque creatingmulti-piston barrel assembly. Due to the inclined mounting of the piston barrel assembly, continuouslyvarying cylinder volumes exist during one revolution. The pistons, therefore, perform strokes similar tothose of an automobile-engine. The high-pressured oil enters and leaves through slots acting asvalves. The piston forces react on the thrust-plate, causing the cylinder barrel and attached shaft torotate with a torque proportional to the supplied oil pressure. The rotation speed of the motor shaftchanges proportionally to the supplied oil-flow.

The hydrostatic motor parameters are:

♦ oil pressure → torque

♦ oil flow (quantity) → speed

These two variables are supplied to the motor by a hydrostatic pump driven by a prime mover and theassociated speed control regulation devices.

Fig. 48: Main components of a hydrostatic variable speed drive system

The hydrostatic pump basically consists of the same elements, only the multi-piston barrel assemblydoes not have a fixed inclined angel. The complete piston unit is designed to swivel about a transversetrunnion axis. At zero degree deflection, all pistons remain axially at the same position, i.e. do notperform any stroke and, therefore, no oil-flow is created. Moving the piston unit out of the straightcentre line, the pistons start to execute a stroke proportional to the deflection angle. An oil flow isestablished and the motor starts to turn at a speed proportional to the deflection angle.



Fig. 49: Plan view of a hydrostatic pump with piston unit at 0 degree deflection

Fig. 50: Plan view of a hydrostatic pump with piston unit at +20 degrees deflection

This is a short introduction to the hydrostatic operating principle. Many additional accessories likevalves, oil cooler, operating protection, torque limiters, emergency shut-down, etc. are not explained,but are available and together with pump and motor form a complete drive system. Good operatingbehaviour and controllability therefore make it truly comparable to electrical variable speed drivesystems.

Engineering / B07 - Eng / C03 - Drive Systems / Drive Systems / 4. VARIABLE SPEED DRIVE SYSTEM / 4.3 Hydraulic variable speeddrive system / 4.3.1 Hydrostatic drives / 4.3.1.1 Application

4.3.1.1 Application

The hydrostatic drive system is widely known and used in the cement industry since approx. 1965.Drives requiring variable speed and high starting torque have been equipped with the above system,e.g. for crusher-feeders, grate coolers, etc. from a few kW-approx.-200 kW. Good reliability and lowmaintenance of this hydromechanical system make it an alternative to electrical drives.

Engineering / B07 - Eng / C03 - Drive Systems / Drive Systems / 4. VARIABLE SPEED DRIVE SYSTEM / 4.3 Hydraulic variable speeddrive system / 4.3.2 Hydrodynamic drives

4.3.2 Hydrodynamic drives

The construction of a hydrodynamic drive is similar to that of a turbine, where rotor and stator are not indirect mechanical contact, but are coupled through a liquid or gaseous medium. A prime mover (e.g.electric motor) drives a hydraulic pump. The medium set in motion by the pump is feeding a hydraulic



turbine which at its output shaft drives the coupled machine requiring smooth-start or variable speed.

Fig. 51: Operating principle of a hydrodynamic coupling

Pump and turbine are brought together and built into one common casing. This combined unit is thencalled hydrodynamic coupling or turbo coupling.

In most commercially used types of couplings, the medium which transports the kinetic energy from thepump to the turbine is oil. The quantity of oil represents a very important parameter since thetransmitted torque and speed depend on the filling degree of the coupling.

Therefore

♦ constant oil volume → coupling

♦ variable oil volume → variable speed drive

In order to achieve a variable oil volume, technical means of adding to and subtracting from the oilvolume have to be established during operation at any speed. This oil quantity e.g. can be varied withan adjustable sliding scoop tube. In this way, the power transmitted by the hydrodynamic coupling canbe adjusted and stepless speed regulation of the driven equipment in accordance with load demands isprovided.

Fig. 52: Schematic diagram of a variable speed hydrodynamic coupling

1) prime mover (e.g. electric motor)

2) hydrodynamic coupling:a : pump, b: turbine

3) oil level in the casing during operation



4) adjustable sliding scoop tube (up and down)

5) output shaft with variable speed depending on scoop tube position

6) heat exchanger

7) oil flow control valve

Engineering / B07 - Eng / C03 - Drive Systems / Drive Systems / 4. VARIABLE SPEED DRIVE SYSTEM / 4.3 Hydraulic variable speeddrive system / 4.3.2 Hydrodynamic drives / 4.3.2.1 Application

4.3.2.1 Application

The hydrodynamic coupling itself behaves according to the propeller law. The output torque increaseswith the square of the input speed. The coupling, therefore, is well-suited to drive machines withparabolic torque load characteristics such as centrifugal pumps and fans with a regulating range of notmore tan 4:1. Machines with a constant torque load characteristic can be used only with a speed rangeof not more than 3:1 and have to be oversized in most cases. Dynamic response of the variable speeddrive system is much slower than e.g. with a DC drive since this depends on the position regulator ofthe scoop tube.

On the other hand, the hydrodynamic offers very interesting benefits since very large units at very highspeed are quite normal. The size ranges from a few kW (approx. 20 kW) up to 8 MW at 12,000 min-1

or 60 MW at 5,000 min-1. Especially the units with extreme speed requirements (very high or low)operate either at the input or output with multiple gear stages.

Many of those very large and high speed units are installed in nuclear and thermal power plants asboiler feed pumps. Others, including the cement industry, use some of the wide variety ofhydrodynamic variable speed drive systems too.

Engineering / B07 - Eng / C03 - Drive Systems / Drive Systems / 4. VARIABLE SPEED DRIVE SYSTEM / 4.3 Hydraulic variable speeddrive system / 4.3.3 Smooth-start by turbo couplings

4.3.3 Smooth-start by turbo couplings

The operating principle of the hydrodynamic or turbo coupling is described in para 4.3.2 above. Themain feature of such a device is not the speed regulation, but the soft start and shock absorbingcharacteristic. The final output speed at the end of the start-up sequence is, therefore, always similarto the input speed. The plain coupling has no scoop tube. One of the special features is the retardedfilling of the oil chamber after stand-sill. During start-up, the integral delayed filling chamber retains partof the operating fluid from the coupling working chamber, resulting in a reduced torque transmissionuntil all the oil has reached the main chamber. This allows the electric motor to start-up under virtuallyno load.

Fig. 53: Principle of operating of the delayed filling chamber



The total oil volume is also a measure to control the maximum transmittable torque. In a multi-motorbelt system, e.g. load balance can be adjusted by the individual oil filling.

Engineering / B07 - Eng / C03 - Drive Systems / Drive Systems / 4. VARIABLE SPEED DRIVE SYSTEM / 4.3 Hydraulic variable speeddrive system / 4.3.3 Smooth-start by turbo couplings / 4.3.3.1 Application

4.3.3.1 Application

The family of hydrodynamic couplings is well-known in the cement industry. Soft or controlled start-upcan be achieved by a slip ring motor and the corresponding size of the rotor resistor. A squirrel cagemotor and a hydrodynamic coupling perform the same task more elegantly. Therefore, heavy startingmachines like long belts, crushers, fans with a large external mass are often equipped withhydrodynamic couplings as well as mechanical items which do not permit excessive starting torquestresses like chains on bucket elevators. This type of coupling is available from 1 kW up to approx.1,500 kW at nominal input speeds of 3,000 min-1 for the small units and 1,000 min-1 for the largerones.

Engineering / B07 - Eng / C03 - Drive Systems / Drive Systems / 5. CRITERIA FOR ASSESSMENT

5. CRITERIA FOR ASSESSMENT

Engineering / B07 - Eng / C03 - Drive Systems / Drive Systems / 5. CRITERIA FOR ASSESSMENT / 5.1 Specifications

5.1 Specifications

In the specifications the operational requirements, standard of manufacture and the stipulated reliabilityhave to be summarized by the user. Apart from the technical details generally given and the ambientconditions, a number of other factors are important for variable-speed drives:

♦ Starting and slow-running characteristics

♦ Speed/torque characteristic of the driven machine and of the selected drive system

♦ Range of operating speed and accuracy

♦ Suitable means of protecting the installation, which does not lead to unnecessary stops in the eventof short interruption of the supply

♦ Definition of the maximum admissible harmonic current content on the network and of the filterequipment

♦ Extent to which the power electronics is proof against short circuits



♦ Cooling for the motor and converter

♦ Redundancy requirements

Engineering / B07 - Eng / C03 - Drive Systems / Drive Systems / 5. CRITERIA FOR ASSESSMENT / 5.2 Reliability

5.2 Reliability

The main objective when using any drive system, be it mechanical or electrical, is to ensure highavailability and reliability for the installation as a whole, with minimum maintenance. The choice ofsystem can to a large extent be influenced by the qualifications of the local staff. This does not onlyapply to electric drive systems; hydromechanical systems today use components and technologieswhich can no longer be regarded as common knowledge for the average mechanic. On the other hand,the electrical industry, by utilizing high-power thyristors and by simplifying the control electronics, ismaking an attempt to keep the complexity of the systems within reasonable limits.

Engineering / B07 - Eng / C03 - Drive Systems / Drive Systems / 5. CRITERIA FOR ASSESSMENT / 5.3 Efficiency

5.3 Efficiency

As far as running costs are concerned, the efficiency at the most frequently used operating point is afactor of decisive importance. In the foreseeable future energy costs will continue to increase at afaster rate than investment costs. Therefore, when planning installations, it is necessary to make acomparison of the investment cost with the operating costs of the potential drive systems. This trendshould be taken into account in the appropriate manner during the evaluation.

The efficiency figures quotated by the manufacturers of drive systems have to be examined with greatcare, as in most cases they only provide an efficiency curve for full load of the most significant drivecomponent, e.g. the motor. Information on partial load is difficult to obtain, but in most cases the valuesare below those quoted.

Engineering / B07 - Eng / C03 - Drive Systems / Drive Systems / 5. CRITERIA FOR ASSESSMENT / 5.3 Efficiency / 5.3.1 Definition oftotal drive system efficiency

5.3.1 Definition of total drive system efficiency

Efficiencies of individual drive components do not define the total system behaviour. For comparison, itis therefore essential to establish meaningful and measurable limits, which define the border lines ofefficiency for one total drive system. On the one hand, the power drawn from the network is measuredand, on the other, the mechanical power imparted at the variable speed shaft. All components locatedbetween these two interfaces are appropriately to be taken into account for any system includingauxiliary power consumption e.g. for cooling or ventilating purposes.

Fig. 54: Definition of total drive system efficiency



Engineering / B07 - Eng / C03 - Drive Systems / Drive Systems / 6. CONCLUSIONS

6. CONCLUSIONS

Especially when high powers are involved, existing and newly planned installations should be closelyexamined to determine whether they are not equipped with drives or control systems involving undulyheavy losses. Using up-to-date techniques, this is a field where it is possible to achieve substantialsavings in running costs.

It may be taken for granted that the present trend towards variable-speed drive systems fed by staticconverters will continue in the future. The development of power and control electronics also allowsone to expect that the outlay for variable-speed a.c. drives will decrease further. The high effieciency ofelectric drives will therefore make their utilization increasingly interesting. The trendency to seek analternative to d.c. motors and thus to get away from their commutator problems, is unmistakeable.Opportunities for this are provided by hydromechanics and three-phase a.c. systems. But even thesesystems require a certain amount of maintenance. It is therefore advisable to analyse all alternativesvery closely. No matter how high the efficiency may be, it loses all its significance if the system failsonly a few times! It will therefore be necessary to weigh reliability and efficiency very thoroughly, oneagainst the other.

Some typical applications of variable-speed drive systems were dealt with in this session. Unfortunatelythere are not generally valid solutions for the various applications in all countries.

Engineering / B07 - Eng / C03 - Drive Systems / Drive Systems / 7. MESSAGES

7. MESSAGES

♦ Be energy conscious when selecting variable speed drives

♦ Consider alternatives and new technologies

♦ Analyse new technologies very thoroughly especially with respect to reliability and efficiency



Engineering / B07 - Eng / C04 - Plant Automation

C04 - Plant Automation



Engineering / B07 - Eng / C04 - Plant Automation / Plant Automation

Plant AutomationRoland Luder

1. INTRODUCTION

2. BENEFITS OF AUTOMATION

2.1 More reliable operation

2.2 Uniform operation

2.3 Energy saving

2.4 Manpower saving

2.5 More efficient maintenance

2.6 Better quality

2.7 Protection of environment

3. AREAS OF AUTOMATION IN A CEMENT PLANT

4. PROCESS AUTOMATION

5. PROCESS AUTOMATION COMPONENTS

6. PROCESS AUTOMATION SYSTEMS

7. CONCLUSION



Engineering / B07 - Eng / C04 - Plant Automation / Plant Automation / 1. INTRODUCTION

1. INTRODUCTION

Automation can be defined as a physical system which is capable of reaching a certain target withoutany human action.

Applied to the cement manufacturing process, different targets can be formulated. One could forexample be: load bags to the packing machine without any human action. The most extreme targetwould be an automatic bank transfer to the shareholders of the dividends of the totally automaticcement manufacturing.

But already the small example of the bag loading shows that automation very soon reaches limits: Anautomatic bag loader today is no longer a problem, but the target "loading bags to the packing machinewithout human action" has by far not be reached. Who does the unloading of the bags? And who doesmaintenance on the bag loader? Theoretically, these activities could also be made automatic, but itwould generally not be feasible and there are of course still limits (e.g. who does the maintenance ofthe "automatic bag loading maintenance machine"?).

When we mention "automation" we nowadays immediately associate computers or electronicequipment to it. This is only natural since almost all automation systems are today based on electroniccomponents. When the term automation system is used it shall therefore mean a system based onelectronic components.

Engineering / B07 - Eng / C04 - Plant Automation / Plant Automation / 2. BENEFITS OF AUTOMATION

2. BENEFITS OF AUTOMATION

The example given in chapter 1 shows that an automation project has to be clearly analysed for itsultimate benefit within the cement manufacturing process. The achievable benefits can generally notbe expressed or calculated in exact figures, automation is always related to or has to be compared withhuman factors and these factors are difficult to determine.

Nevertheless, some fields where automation can yield some benefits shall be further elaborated:

Engineering / B07 - Eng / C04 - Plant Automation / Plant Automation / 2. BENEFITS OF AUTOMATION / 2.1 More reliable operation

2.1 More reliable operation

The installation of modern electronic equipment instead of elector-mechanical components guaranteesa higher reliability of the control system. Equipment downtime can be reduced due to the availability ofdetailed process warnings.

Engineering / B07 - Eng / C04 - Plant Automation / Plant Automation / 2. BENEFITS OF AUTOMATION / 2.2 Uniform operation

2.2 Uniform operation

The operator is released from all routine operations, checking and controlling. He is thus in a positionto fully concentrate on the optimum and efficient operation of the process. In this objective he is greatlysupported by the system which presents all relevant information in a logic and easily understandableway.

Engineering / B07 - Eng / C04 - Plant Automation / Plant Automation / 2. BENEFITS OF AUTOMATION / 2.3 Energy saving



2.3 Energy saving

A modern control system automatically starts and stops motors according to the process requirements.Inefficient continuous running of motors and high energy losses during unproductive start-up trials areeliminated. The control system can easily include the control of the peak load to the plant (energymanagement). A better stabilised process can have a very positive influence on thermal as well as onelectrical energy consumption.

Engineering / B07 - Eng / C04 - Plant Automation / Plant Automation / 2. BENEFITS OF AUTOMATION / 2.4 Manpower saving

2.4 Manpower saving

Achievable savings depend on actual labour situations, labour costs, labour policies (unions) etc.

Engineering / B07 - Eng / C04 - Plant Automation / Plant Automation / 2. BENEFITS OF AUTOMATION / 2.5 More efficientmaintenance

2.5 More efficient maintenance

The maintenance on control and instrumentation can be kept to a minimum due to the installation ofelectronic equipment. No time-consuming troubleshooting will be required since failures are displayedin clear text. Mechanical maintenance can be optimised and preventive maintenance can be introduceddue to the availability of detailed failure and warning messages and statistical evaluation of all events.

Engineering / B07 - Eng / C04 - Plant Automation / Plant Automation / 2. BENEFITS OF AUTOMATION / 2.6 Better quality

2.6 Better quality

The market demands for less tolerances in the cement quality. An uniform operation, more preciseon-line measurements are a guarantee also for better quality.

Engineering / B07 - Eng / C04 - Plant Automation / Plant Automation / 2. BENEFITS OF AUTOMATION / 2.7 Protection of environment

2.7 Protection of environment

A modern automation system not only controls the process, it is furthermore and more responsible forcontinuous environmental protection.

Example: Exhaust gas analysisWaste water treatmentEnergy management

The given examples are typical closed loop control systems. Thus, it is not dependent on humanobserving abnormalities and reactings. It is a continuous process acting in very narrow limits.

Engineering / B07 - Eng / C04 - Plant Automation / Plant Automation / 3. AREAS OF AUTOMATION IN A CEMENT PLANT

3. AREAS OF AUTOMATION IN A CEMENT PLANT

Automation can be applied in many different fields of the cement manufacturing process.

Table 1 gives an overview of those fields which are mainly concerned with automation. It also showswhat type of hardware normally is applied to perform this automation.



The table clearly shows that a vast variety of equipment can be used for the different automation tasks.When it comes to software this variety is even bigger. In order not to end up with a patchwork ofdifferent automation systems, it is therefore very essential to carefully plan and to evaluate anyautomation project. It is mainly important to always keep the entire process and the entire system inmind. Automation can start with the modernisation of a single machine, but the automation or control ofthis single machine should be designed from the beginning to fit into an overall automation concept.

Table 1

AUTOMATION AREA AUTOMATION HARDWARE

1) QUARRY CONTROL

Quarry planning Workstations, PC's

2) PROCESS AUTOMATION

Motor controlProcess controlMonitoring

Programmable controllersPC's, WorkstationsGraphics DisplaysProcess computers

3) DISPATCH CONTROL

LoadingAdministration

Programmable controllersWorkstations, PC's

4) QUALITY CONTROL

Sampling preparationX-rayOn-line raw mix control

Programmable controllersIncluding micro-computersPC's, Workstations

5) MAINTENANCE

Materials managementMaintenance planningReporting, documentation

WorkstationsPersonal computers

6) MANAGEMENT INFORMATION,ADMINISTRATION

Production reports, statisticsCommercial dataPersonnel administration

WorkstationsPersonal computers

Engineering / B07 - Eng / C04 - Plant Automation / Plant Automation / 4. PROCESS AUTOMATION

4. PROCESS AUTOMATION

The next chapters will concentrate on process control and some aspects of management informationonly. The other fields of automation are mainly dealt within the respective chapters.

Process automation or process control has become more and more important together with theincreasing capacity and complexity of cement plants. Table 2 shows how the number of drives andinstruments (which can be used as degree of complexity) has increased in the last decades. Thefigures given represent very approximate values of a medium-size cement production line.

The technology of control system components has drastically changed during these periods, whereby



most new developments have been based on the respective underlying developments in the field ofelectronic/computer technology.

To predict the future is of course always a difficult task. Some trends, however, can already beobserved. One trend is surely that there will be developments for more memory at a lower price whichwill allow better and faster information handling. This again will have an influence in the furtherdevelopment of self-learning ("expert" or "intelligent") systems.

The trend in graphic displays goes towards bigger, flatter screens with higher resolution.

An additional tool as operator interface might be the development in voice information or voicecommand. For the moment it is, however, more of a nice game than an efficient tool to increaseproduction.

Table 2

- 1940 Local control of individual machine, localpneumatic/mechanical indication50 motors, 20 instruments

- 1960 Central control rooms , sequence control of motors(relay), remote indicatin of instruments200 motors, 70 instruments

- 1975 Central control rooms, decentralised programmablecontrollers, monitoring or process computers400 motors, 150 instruments

- 1985 Central control rooms, centralised controllers withremote input/outputs, graphic displays, data-highways800 motors, 300 instruments

- 1990 Central control rooms, distributed control systems,automated documentation tool, integration ofmanagement information1000 motors, 500 instruments

future Integration of expert knowledge, voice command, use oftransputers, field bus to the level of transmitters,intelligent sensors

Engineering / B07 - Eng / C04 - Plant Automation / Plant Automation / 5. PROCESS AUTOMATION COMPONENTS

5. PROCESS AUTOMATION COMPONENTS

The different main components of a process automation system are shown as the three lower levels ofthe pyramid in Fig. F49591 "Structure of plant automation".

The total system of these component functions in a similar way as a human being:

Sensors and the cabling perform similar tasks as the nerves - capturing and transmission ofinformation to the brain.

The controller performs similar jobs as the brain. It processes the information.

The result of this data processing is transmitted again by the nerves to the muscles which transformthe information into a physical movement as in a plant control system, where the controller output is



transmitted - again over cables - to the actuator or the MCC where the information is transformed intophysical power.

Needless to say, a plant control system plays a very important part in the performance of a plant,similar to the one of the brain and the nerves of a human being.

The individual components "analogue sensor/transmitter" will be further explained in the chapterSENSORS, the component "logic controller" in the chapter MOTOR CONTROL.

In order to understand the subdivision process controller / logic controller / computer / man-machineinterface within the so called "integrated controller" one has to go a little bit back in history of controlsystems.

Some years ago the subdivision of an automation system into the parts

• motor control

• instrumentation and process control

• data logging

used to be clearly defined by the corresponding type of equipment:

• relays, then programmable controllers for motor control

• separate instruments and closed loop controllers for process control

• recorders and operators day-book, then computer data logging equipment.

Every type of equipment used to have its own type of man/machine interface

• push-buttons and lamps for motor control

• potentiometers and instruments for process control

• keyboards and displays for data logging.

This control equipment has also been offered from more or less specialised manufacturers, as e.g.:

• Modicon for Motor Control

• Honeywell for Instrumentation

• Digital Equipment for Data logging

Today there is a market tendency for the established manufacturers to expand outside the field inwhich they have hitherto specialised and to enter the other areas of automation more and more; thismeans that modern programmable controllers can perform process control tasks and condition data;computer systems are also able to perform sequence control and they are all linked by computer bussystems and networks.

Engineering / B07 - Eng / C04 - Plant Automation / Plant Automation / 6. PROCESS AUTOMATION SYSTEMS

6. PROCESS AUTOMATION SYSTEMS

For the automation of a cement plant which has to combine all the three functions of motor control,process control and data logging, it is thus possible to select the most appropriate component for eachof the three areas and to integrate them in a complete system. In practice, though, this procedure isoften obstructed by the lack of compatibility of the units (i.e. difficulty in interconnecting them) because,owing to the rapid progress made in electronics, neither hardware nor software are sufficientlystandardised. Furthermore, the user is confronted with the problem of maintaining three inherentlydifferent systems.

Fortunately, we have seen that manufacturers have expanded their fields of activity and that today, a



level has been reached where all three functions can be realised with only one or perhaps two differentcontrol systems.

The structures of complete systems from different suppliers, however, still shows considerabledifferences.

Since in the cement industry motor control represents the most extensive part of the automationsystem, it is regarded to be optimal to choose a programmable controller as basic control unit.

Among the various types of programmable controllers available (in Switzerland about 130manufacturers are represented on the market), it is the medium to large units that are most suitable forthe cement industry. "Large" units are regarded as being those capable of catering for the motor andprocess control of a complete department (e.g. raw mill) with all the associated processing of data forthe man/machine interface. As regards configuration, documentation and ease of modification, largesystems are preferable to a number of medium or small units.

With this concept the automation system of a complete cement production line generally consists ofone programmable controller for each department (crusher, raw mill, kiln, cement mill, coal mill, cementdispatch), each controller with its separate operator station and each performing motor control as wellas process control. For general management information and reporting, the operator stations areinterconnected and linked to a separate data base computer being part of the information managementsystem.

♦ Power supply:In order to absorb brief interruptions of the plant voltage and in order to correctly alarm any realvoltage supply failure, it is recommended to connect the entire control system to an uninterruptedpower supply.

♦ Test system:The spare parts required for the automation system are preferably assembled to form a "testsystem". This system should be procured before anything else in order that the software can be setup and tested before the actual process control system is installed. After commissioning, the testsystem is used as "spare parts stock" as well as for testing possible changes to the programs andalso for training new personnel. Naturally, the "spare parts stock" has to be replenished accordingto the consumption.

♦ System documentation:To establish the system documentation, every possible use should be made of the facilities offeredby computers today. A special chapter will be allocated to this topic.

♦ Communication:A good communication system can help a lot to improve efficiency in operation and maintenance.Here, too, a clear concept should be established. All possible methods:

• telephone/paging, walkie-talkie, intercom, loudspeaker, fax, video etc.should be considered and possible applications evaluated.

Engineering / B07 - Eng / C04 - Plant Automation / Plant Automation / 7. CONCLUSION

7. CONCLUSION

Modern process automation systems can contribute a lot to the enhancement of the efficiency of plantoperation. Nevertheless, the degree of the most feasible level of automation has to be carefullyevaluated. And most important: even the highest automated plant needs a good maintenance in orderto run efficiently. Or in other words: The most luxurious process control system with the most brilliantgraphic displays cannot guarantee smooth operation if it does not receive reliable, correct information



from the sensors.



Engineering / B07 - Eng / C04 - Plant Automation / Modernization of Control and Supervisory Systems in the Cement Industry1

Modernization of Control and Supervisory Systems in the CementIndustry1(1)

Rene Säuberli

1. REASONS FOR MODERNIZING CONTROL SYSTEMS

2. PLANNING OF MODERNIZATION PROJECTS

3. DESIGN OF A CONTROL SYSTEM

4. PRACTICAL ASPECTS OF THE EXECUTION OF MODERNIZATION PROJECTS



At times when financial means are restricted and the competitive situation on the market is tense, allefforts must be directed towards savings - and thus towards optimization - of the production processand maintenance. Modern technologies in the plant control and monitoring systems can contributeappreciably to a reduction in costs, provided they are properly applied.

Engineering / B07 - Eng / C04 - Plant Automation / Modernization of Control and Supervisory Systems in the Cement Industry1 / 1.REASONS FOR MODERNIZING CONTROL SYSTEMS

1. REASONS FOR MODERNIZING CONTROL SYSTEMS

Depending on the plant concerned and its environmental conditions, there can be a variety of reasonsfor undertaking modernization projects. Generally speaking, though, the main reasons for suchprojects are one or more of the following:

a) Plant and equipment is worn out and requires too much, too expensive maintenance

b) The plant or system is no longer reliable enough

c) Owing to a lack of spare parts the plant or system can no longer be repaired

d) Maintenance agreements are expensive

e) The plant or system does not permit any further automation of the production process

f) The system does not permit any further optimization of the process, the information, themaintenance and /or energy consumption

g) Environmental conditions, such as public opinion, environmental protection, emission limits, etc.,make further use of a system or process questionable.

Item c) above points to a new aspect of electro-mechanical equipment, that if its “maintainability”. Thisaspect is very important and therefore deserves to be discussed at greater length, especially becausein most cases works managements fail to attach sufficient importance to it. The conventional mode oflooking at maintainability is restricted to the ease of maintenance, when components, machines orsystems have to be maintained or replaced because they are showing signs of wear or old age. Thesame also applies to automation systems, but here a new aspect of maintenance becomes apparent,that of systems having to be replaced because, due to technological changes, systems or theircomponents become obsolescent without being “worn out”.

The extremely rapid evolution of electronics, together with the low cost of hardware, has providedadvantages as regards reliability, usability and application potential. On the other hand, this rapidevolution has resulted in a reduction in the useful life, especially on account of the short presence onthe market of certain electronic components. In other words, components which only appeared on themarket five or ten years go, can no longer be supplied.

The replacement of electronic equipment gives rise to problems, in that electronic units cannot simplybe replaced by new products. The reason for this is that standardization is hardly possible, on the onehand owing to the very rapid evolution and, on the other, due to the growing complexity of the units.For this reason, it may be impossible for a manufacturer to design his own products so that they arecompatible. The presence on the market of a modern electronic control system may be assumed tolast for about seven years, i.e. about one third of the normal life of a machine that is controlled by it. Inother words, nowadays a machine outlives roughly three generations of electronic units.

Fortunately, though, there are signs that the situation with regard to compatibility of electroniccomponents is slowly but surely improving. But despite this the trend will not produce material effectsat one. The users of the present - and the next - generations of control and supervisory systems will for



the present have to put up with the fact that their systems become obsolete much earlier than desired.

Figure Control system layoutTypical arrangement per department

Engineering / B07 - Eng / C04 - Plant Automation / Modernization of Control and Supervisory Systems in the Cement Industry1 / 2.PLANNING OF MODERNIZATION PROJECTS

2. PLANNING OF MODERNIZATION PROJECTS

Although nobody will question the ability of modern electronic equipment to improve operationalsequences, the task of determining the return on investment for such a project is highly complex anddiffers from one plant to another. The properties of an electronic control system compared with aconventional system have here to be viewed in the light of human factors, i.e. direct human interventionas opposed to automatic operation, human errors compared with the dependability of electroniccomponents, human negligence compared with the robot-like stability of programmed controlsequences. How can these factors be taken into account in a feasibility calculation? The advantagesattainable with modernization projects should always be measured against the existing equipment andactual operational procedure. To do this the first step is always to analyse the momentary state.

Modernization projects for the control and monitoring systems in cement works should be included inthe long-term planning of the company. The momentary state of maintenance, maintainability andperformance of the existing system has to be determined from time to time, in order that the start ofmodernization can be specified without haste. If the replacement of obsolete equipment were suddenlyrendered necessary, this could give rise to some unforeseen shutdowns in the plant. If suchunscheduled replacement measures occur frequently, it will be automatically necessary to replace theentire system step by step, without having achieved any structural improvements, or profiting from newtechnologies, i.e. the whole job is only patachwork. Then, in the end, the whole system may be evenmore complicated than it was before. To avoid this, it is always advisable to keep pace with modernstandard by replacing a control system as soon as important parts no longer perform their functionssatisfactorily or are no longer obtainable on the market.

The planning of a modernization project must begin with a detailed assessment of the existing facilities.This should cover the following points:

1) Determination of the momentary state.

2) Specification of a strategy with regard to the technical and operation objectives which shows inwhat steps, in what time and at what costs they are to be attained.

The difficulty in such an assessment is that the various staff members in the works have with time



become blind to what is going on and - despite their best intentions - are no longer able to recognizethe significant and the really crucial points. It is therefore recommended in all earnest that externaladvisors be entrusted with this task. But the production and maintenance managers of the works mustbe included in the planning process as early as possible.

Planning becomes particularly important when modernization projects are involved, especially forcontrol and supervisory systems. This is reflected in the costs: the outlay on planning and engineeringof the modernization of a control system can amount to more than half the total cost of the project. Awell thought-out control concept also takes into account aspects of changes in technology and themaintainability, as outlined earlier on. The components of such a system are therefore “designed to bereplaced”. That may sound somewhat strange, “designed to be replaced”, but it does correspond fairlyaccurately to the prevailing circumstances.

Engineering / B07 - Eng / C04 - Plant Automation / Modernization of Control and Supervisory Systems in the Cement Industry1 / 3.DESIGN OF A CONTROL SYSTEM

3. DESIGN OF A CONTROL SYSTEM

The control units available on the market can be combined to form an almost unlimited number ofcontrol systems. Therefore, the choice of suitable units and of the most suitable system for a givenapplication should not be left entirely to the suppliers and/or the users.

One must be fully aware of the fact that “control” does not consist solely of the instruments and graphicmonitors in the control room. They are merely the visible part, the “tip of the iceberg” so-to-speak. Thesuppliers of electronic units generally tend to offer only this “tip of the iceberg”, which nowadays is thecheapest part of the whole control system .The rest of the “iceberg” is generally ignored by the supplieror he simply leaves it to his customer, although that is usually more than he can cope with, when itcomes to a full estimate of all aspects of the modernization project. For a user it is normally difficult toanalyse his own requirements, to analyse the market correctly and to employ the most suitableengineering tools. The following are some design principles which have been successfully applied byHMC/TC to a number of cement works in past years.

a) A control/automation system should be constructed from the bottom upwards.

b) The existing facilities for sub-dividing the cement production process into independent sub-units(departments) should also be taken into account when designing the control system.

c) Owing to its importance for the operation of the works, an automation system should primarily beselected with regard to its reliability and maintainability, i.e. it should be as simple as possible.

d) An automation system must be designed in such a way that future requirements can be satisfiedeasily and the replacement of obsolete parts is facilitated.

Requirement a) signifies that a start must be made on the concept at the lowest level of control tasks.This includes the numbering system (labelling, the wiring, the standardization of sensors and signalgenerators, the detailed emission of first alarms, the control and the supervision of auxiliary functions,and so on. All of these have a very definite influence on the overall performance of the system as awhole, where performance applies not only to the execution of functions, but also to the maintainability,extendibility, ease of future replacement, etc. Poor design at his lowest level can possibly becompensated by using additional computers at higher levels of the system. But the overall structureand, thus, the factors mentioned under c) are certain to be affected by such a procedure.

Point b) is taken to imply that each department should be decentralized as far as possible. Onlygeneral functions of a plant, e.g. reporting, statistics, documentation, process optimization, should bedealt with centrally. This enables the departmental maintenance of the control system to be practised



without any risk of causing a stoppage in other departments.

Point c) says that the system should be s simple as possible, i.e. it should consist of a minimum of“black boxes” with a minimal number of standardized connections between them. In this context a“black box” means a hardware or software unit, requiring no internal maintenance or adaptation.

Point d) implies that even the most modern control system does not exist as long as the machines inthe cement industry. It is therefore very important to set the standards for the introduction of newcontrol or automation tasks to the existing control system well in advance and even to plan for thefuture replacement of the whole system. That corresponds to what is meant by “designed to bereplaced”. Experience has proved that a decentralized, standardized control system can satisfy suchdemands very effectively. By replacing in easy stages, spare parts are made available for the stillexisting system, which is not to be replaced yet in all departments. Another positive aspect of thismode of procedure is the improved distribution of the investment costs over a period of time, withoutincurring greater risks for availability of the spare parts.

As the result of such considerations, HMC/TC has developed and put into practice an integrated,decentralized control system, tailored to the needs of the cement industry. The diagram shows thestructure of the system schematically for one department of a plant (for all the other departments thestructure remains in principle the same). In a system of this kind each main unit e.g. a programmablelogic controller (PLC) processes the signals of the motor control and simultaneously those of theinstrumentation. The following advantages accrue from this procedure:

♦ Only one make of units is required.

♦ The interlocks between analog (process) signals and the motor control can be effected direct - atthe lowest level - without wiring or without using the data highway. On account of the high reliability,analog sensors are increasingly being used for the protection of machines (e.g. analog temperaturemeasurement in motor windings or gear bearings, for the measurement of oil flow, etc.). In anintegrated system these sensors are wired direct to the PLC. Preliminary alarms, shutdown alarmsand the shutdown interlocks are programmed in the same unit.

♦ The alarms from digital or analog signals are given by the same unit; there is only one kind of alarmprocessing. Alarms from the process can easily be interlocked with operating conditions of themotors, for example.

♦ Control of a variable-speed drive is very easy (start/stop = motor control; changing speed = processcontrol). Dividing these two tasks between two separate units/would unnecessarily complicate thesystem. In view of the growing number of variable-speed drives, the integration becomes more andmore important.

♦ Closed control loops can be easily integrated, in order that hey can meet the various conditionsduring starting and stopping operations.

♦ Hardware and software can be largely standardized, each department using the same type of blackbox (hardware and software). Since all the control functions are allocated, the correspondingsoftware does not have to be nearly as intricate as in a centralized system.

The computer capacity and the facilities for direct operation of displays by the central unit must beutilized as man-machine interface, thus achieving a fully integrated system. If the selected central unitdoes not offer enough scope, modern microcomputers or personal computers should be employed. Inthis case the microcomputer calls all the information required off the main unit. However, it should notbe used to initiate any intervention in the process, but should remain exclusively reserved for theefficient processing of information. All control commands and motor/process interlocks, sequences,etc., should be processed direct by the central unit.



Engineering / B07 - Eng / C04 - Plant Automation / Modernization of Control and Supervisory Systems in the Cement Industry1 / 4.PRACTICAL ASPECTS OF THE EXECUTION OF MODERNIZATION PROJECTS

4. PRACTICAL ASPECTS OF THE EXECUTION OF MODERNIZATION PROJECTS

As guidelines for the execution of modernization projects the following general rules have proved theirworth in the past.

a) The control system should not be included in the scope of delivery of the machinery supplier,because he looks for the system that will be most economical for his own purposes. The customer,however, has to make sure that he is going to receive the system that will be most economical forhis process, in which maintenance and future developments of the plant have also to be taken intoaccount (integrated system). The only exceptions where the control system should be included inthe delivered package are the very special control systems for electronic weighing equipment onbagging machines or for the power electronics associated with drives, etc.

b) The equipment numbering system must be examined to make sure that all parts can be clearlyidentified. Can the system also be used for detailed indication of events and alarms, for dataacquisition and for electrical and mechanical maintenance?

c) The safety regulations (existing and planned) in the user’s own country must be examined veryclosely before the appropriate safety concept is drawn up. It must be checked whether local stopswitches for each motor are sufficient or whether a main isolator has to be provided next to themotor. Where do pullcord switches have to be installed? What warning devices (horns, sirens,flashing lights, etc.) are needed when starting up the machines and where are “panic stops”necessary?

d) The existing wiring has to be examined and a clear wiring concept drawn up. The wiring should besuch that it is not affected if the control system is replaced at some time in the future. An adequatenumber of spare lines must be available, should it be necessary to extend to monitoring of theprocess by additional sensors. These will have to be individually wired also in the future. It istherefore essential to consider carefully how this lowest level of the system should be designed, tobe standardized and as simple as possible.

e) Dependable, standarized interfaces should be provided in the control system and with all externalcontrol sub-systems (hardware and software). Problems are usually caused in control systems byunclear, complicated or uncertain communication processes and/or interfaces. The communicationproblem, however, cannot be solved by installing a data highway or bus, a local network or similarfacility. They are merely tools like a telephone or telex. What is important is the contents of themessage or information that is to be transmitted and its interpretation by the receiver.

f) Sufficient time must be spent on drawing up a clear concept and on adequately detailed basicengineering, before any system is purchased. All functions to be performed by the automationsystem - as well as those it has not to perform - must be clearly defined in advance. As far aspossible, employees from production and maintenance should be included in this planning. It isindeed true that modern control systems permit a program to be simply changed, but that is onlytrue of minor changes. Major changes in the concept are never simple: that is why a detailedspecification of the system and its components is so important. The degree of automation has to beestimated very carefully. The higher this degree of automation is, the greater the number ofdecisions that have to be programmed in advance and the more complicated and expensiveprogramming becomes. The aim of the specification of a control system is to stipulate the optimaldegree of automation for every single task.

g) A detailed alarm system has to be specified. This system is one of the deciding points in the



improvement of operation and maintenance.

h) The complete system has to be tested before it is installed, especially the communicationinterfaces. In this phase it is important to include the works personnel.

i) The spare parts have to be purchased as early as possible and utilized in the construction of atraining system. This enables the works personnel to become familiar with the new system at anearly date. A system of this kind, composed of spare parts, can later be used for testing programs,as a training centre and as a “stock for warming up” these spares.

j) An important factor is the careful compilation of the documentation for the equipment and spareparts. It is well worth while to store the documentation on the computer from the very start ofmodernization. Experience has proved that existing documentation is usually out of date and has tobe renewed in any case. Computerizing - when it is carefully planned and carried out - is a goodmethod of ensuring that the documentation no longer becomes out of date.



Engineering / B07 - Eng / C05 - Sensors

C05 - Sensors



Engineering / B07 - Eng / C05 - Sensors / Sensors

SensorsWolfgang Kornberger

1. INTRODUCTION

2. SENSORS (INSTRUMENTATION) BASICS

2.1 Terminology

3. SIGNAL TRANSMITTER

4. SIGNALS

5. SIGNAL TRANSMISSION

5.1 Current output

5.2 “DEAD ZERO” and “LIVE ZERO”

5.3 Power supply

5.4 4-wire and 2-wire transmitters

5.5 Non-isolating and isolating transmitters

6. CONTROL, ALARMING AND DISPLAY

7. MEASUREMENT USED IN THE CEMENT INDUSTRY

7.1 Temperature

7.2 Pressure

7.3 Flow (gas and liquids)

7.4 Level

7.5 Weighing

7.6 Analytical measurements

7.7 Electrical energy and power measurements

7.8 Field devices



Engineering / B07 - Eng / C05 - Sensors / Sensors / 1. INTRODUCTION

1. INTRODUCTION

When looking at the automation pyramid, it becomes obvious that instruments and sensors form thefoundation for any control and automation. It is here where the information is gathered which is thenused further in the automation pyramid for either:

♦ interlocking and control for automated production

♦ regulation with PID-controller and high level control to ease the workload of the operator and toimprove the plant performance (reduce energy consumption and/or increase production)

♦ display and register process values to inform the management and the operator about the plantperformance

Note: It is important to remember that it is impossible to control anything unless the parameters havebeen accurately measured in advance.

Engineering / B07 - Eng / C05 - Sensors / Sensors / 2. SENSORS (INSTRUMENTATION) BASICS

2. SENSORS (INSTRUMENTATION) BASICS

The task of an instrument or a sensor is to convert a physical value into an electrical signal. A signal ispicked up with a primary element, then converted in the transmitter to an electrical signal and finallytransmitted to a control centre where the signal is further treated for either display, alarming or control.(See drawing F44570-1)

The example in the drawing F44570-1 shows a pressure transmitter. The pressure (connected oneither side) distorts the bellows. This deformation is moving a lever which is connected to a plungermoving in a coil. The movement of the plunger in the coil evokes an electrical signal which then isconverted to a standard electrical signal of 4-20 mA.

All transmitters work on a physical principle which depends on the process media, the desired type ofmeasurement and the accuracy required. Some principles are as simple as in the example in drawingF44570-1 given. Others, like gas analysers working on light diffraction are more sophisticated andtherefore not only more expensive but as well prone to high maintenance.

Engineering / B07 - Eng / C05 - Sensors / Sensors / 2. SENSORS (INSTRUMENTATION) BASICS / 2.1 Terminology



2.1 Terminology

Like in all engineering fields, instrumentation has its own kind of terminology; and to be able to read atechnical specification these terms have to be known. The following list gives a short overview of themost important terms used.

Example Ampere meter .5% accuracyTemperature meter ± 5o C

Accuracy: A number of quantity (usually expressed in % full scale) which defines the maximum error.

Calibration: The ascertain by the use of a standard the locations at which scale or chart graduation of aninstrument should be placed to correspond to the required value.

To adjust the output of an instrument to bring the desired value within a specified tolerance.

Deadband: The range throughout which an input can be varied without initiating response. Deadband is usuallyexpressed in percent of full span.

Deadtime: The interval of time between initiation of an input and the start of the resulting response.

Damping Reducing of the oscillation of a process input or the output of a controller.

Drift: Undesired change of an output over a period of time.

Deviation: Departure from a desired or expected value also difference between measured value and true value.

Error: (see drift) Error = indication minus true value = setpoint minus measured value

Elevated Zero: A range where the zero value is greater than the lower range value.

Feedback: Positive answer to a demand in change

Gain: Is the ratio of an output change to an input change. (Reciprocal to proportional band).

Hysteresis: The maximum difference between the upscale and downscale indications of the measured signalduring a full range traverse for the same input.



(Alarm limits for example are equipped with a hysteresis in order to prevent repeated signals aroundthe alarm point).

Impedance: Resistance of a network of resistors, capacitors and/orinductors.

Interference: Noise (spurious voltage or current arising from externalsources or interference between measuring circuit andground).

Input: Device to convert the electrical signal into a digital informationfor further treatment in a Process Station or ProgrammableLogic Controller (PLC).

Linearity: The closeness to which a curve approximates a straight line.

Limit: Alarm limit

Lag: (Time lag) time elapsed between process and measuringpoint as well as measuring point and control device.

Noise: False signal picked up in the transmission line (seeinterference and signal-to-noise ratio).

Output: Signal from a device (instrument).



Output: Signal from a device (instrument).

Range: Region between limits of measuring device expressed bystating the lower and upper range values.

Response: General behaviour of the output of a device as a function of an input.



For additional information regarding PID control refer to the relevant paper in the process technologydepartment.

Sensitivity: (see deadband and gain).

Signal toNoise Ratio:

Ratio of signal amplitude to noise amplitude.

Span: The algebraic difference between the upper and lower rangevalues.

Suppressedzero:

The zero value of the measured variable is less than thelower range value. (Zero does not appear the scale).

Time constant: Time required for an output of an instrument to complete 62.3% of the total rise or decay.

Zero: Zero point of scale (to be calibrated frequently due to zeroshift resulting in parallel shift of the input output curve).

Engineering / B07 - Eng / C05 - Sensors / Sensors / 3. SIGNAL TRANSMITTER

3. SIGNAL TRANSMITTER

As mentioned in the introduction, the task of the transmitter is to convert a physical signal into asuitable electrical signal. This electrical signal is then converted into a standard analogue signal of forexample 4-20 mA or 24 V digital on/off. Other standard signals exist but the “Holderbank” standardanalogue signal is 4-20 mA, for digital on/off signal 24 VDC (Exception America: 110 VAC).

It is, in most cases, necessary to calibrate or verify (adjust zero, span and range) a transmitter. Normaladjustments are Zero = 4 mA and Span = 20 mA. Thus the actual electrical signal representing aprocess value of 0 - 100% is represented by 16 mA. Calibration is usually performed by simulating thephysical signal. Thus, a true zero and if feasible a 100% signal should be evoked in order to calibratethe transmitter over the entire range. The smaller the range of the calibration signal is the moreinaccurate the calibration. Each type of instrument transmitters requires its particular way of calibration.It is therefore mandatory to provide the proper instruments for calibration purpose. Additionally, it isimportant not only to calibrate the transmitter but the entire instrument loop. Thus, the transmission andthe signal treatment in either a display instrument or a PLC must be included in the calibrationprocedure. (See drawing F44570-1)

Some modern instruments require an initial calibration during commissioning and only an occasionalcheck up during their lifetime. Others, like for example power transducers cannot be calibrated nor dothey require any adjustments since they are factory precept.

The instruments described above are analogue instruments. That’s why the signal varies continuouslybetween 0 and 100%. Often, however only one single point is required. For such a purpose a sensorwith an on/off output is sufficient. It saves programming of an alarm limit in case a PLC is used,respective the use of an extra alarm device to produce a thresh hold. However, using an on/off deviceonly can be controversial since this device cannot be checked about its proper function. A 4-20 mAsignal can be supervised if it is functioning properly (signal <20 mA and signal >4 mA). An on/off signalcan be connected fail safe (contact closed under healthy condition) and a dynamic supervision (contactchanges when the process is stopped) included but an analogue signal is easier to verify.



The trend of automation in process engineering leads to “intelligent” field devices. A new generation ofinstruments called “smart sensors” is on the market. A smart sensor cannot only perform its dedicatedtask (e.g. measure the temperature) but monitor its performance at the same time. These smartsensors are microprocessor-based field instruments which are designed to communicate with a controlunit. A lot of these sensors are operated via hand-held terminals or PC’s. Usually the signal picked upby the primary element is converted into a digital signal by an analogue to digital converter. The digitalsignal is linearized, ranged (0-100% as required), dampened and if required multiplied or squared. Themicro controller also controls the digital-to-analogue signal converter for 4-20 mA output and drives thedigital communication.

Configuration- and sensor linearization data are stored in a non-volatile EPROM memory. The controlunit communicates via a superimposed digital signal over the 4-20 mA signal or via a bus with thesmart sensor.

Each manufacturer has his own communication carrier (bus or via frequency shift keying FSK) over the4-20 mA signal and his own protocol. Usually communication is performed without interrupting thecontrol loop. Some of the following tests and functions can be carried out via link, smart sensor andcontrol unit:

♦ loop test of the 4-20 mA signal

♦ inject a specific mA signal and check the display

♦ check the configuration data and call up its values

♦ check changes of the performance of the smart sensor

♦ name (tag) a device and give an alarm or message text in the smart sensor. Store data aboutspare parts for the device.

Today, neither in the operator control unit nor in the operator philosophy a compatibility orstandardisation is discernible. Due to this situation user acceptance is very low. Additionally, the tasksas mentioned can be performed by the “normal” transmitters connected to a PLC. Thus, it remainsquestionable to whether smart sensors and Profibus are required today for the cement industry.

The enclosed instrument list shows the most frequent measurements applied in the cement industryand the approximate amount of instruments. The number of measurement, approximately 3000,applied in a modern cement plant is quite impressive. And the tendency is certainly not diminishing inthe near future. Especially in connection with environmental control and with rising energy prices, thenumber of additional measurements will increase.

Engineering / B07 - Eng / C05 - Sensors / Sensors / 4. SIGNALS



4. SIGNALS

When talking about signals at first two different sides must be distinguished:

♦ the primary side is the actual physical measurement which is detected with the primary element(e.g. thermocouple, diaphragm of a pressure transmitter)

♦ the secondary side is the signal leaving the transmitter and being transmitted back to the controlcentre.

This and the next chapters deal with the signal transmitted to the control system since this is animportant factor for the installation. When looking at the secondary side of the signal transmission fourdifferent signals have to be distinguished:

1) Analoguesignal

1) → current e.g. 4-20 mA DC, or voltage e.g. 2-10V DC

2) On/off signal 1) → on/off e.g. 24V DC

3) Pulse 1) → frequency e.g. speed detector pulse

4) Field Bus 1) → code e.g. 500°C as a BCD code

The cement industry is concerned with all four types of signals. In the field it is mainly the analogue4-20 mA and digital 24V DC; to a lesser extend with pulses and, if at all, they are converted as soon aspossible to an analogue signal. The classical cement industry was not concerned with a bus except forcommunication between PLC’s or computers. However, the market shows that the near future is in theapplication of the Fieldbus. The respective standards are set and respective commercial advantagesresult. The signals 1) - 3) will become less important.

Engineering / B07 - Eng / C05 - Sensors / Sensors / 5. SIGNAL TRANSMISSION

5. SIGNAL TRANSMISSION

For safe and efficient operation of the plant it is most important to have a reliable signal transmissionbetween the field, - where the signal is generated, - and the control room, - where it is used forindication, recording, limit supervision, process control etc. The distances from the filed to the controlcentre may range between 100 meters and 1000 meters, or more. And it is well known that problemswith electrical disturbance, interference, noise and losses, increase with longer transmission distances.

For signals as mentioned in the previous chapter, several alternatives for the long distancetransmission are applied; some of them are becoming obsolete due to new developments in the filed ofelectronic components.The simplest method would be to run any sort of signals (pressure, electrical)back to the control room as performed in the early stage of instrumentation when the control centrewas local and closed by. On the example of a thermocouple (TC), the problems encountered arediscussed.

Is it possible to run a thermocouple extension wire with a mV signal all the way from the thermocouplejunction to the indication in the control room? Why not? Mainly because the thermocouple extensionwire is expensive. And unless it is very well shielded, which adds to the expense, it will pick-up all sortsof unwanted noise from radio transmitters (walkie-talkies), motors, high voltage cables etc. Since thesignal from the thermocouple is only a few milli-volts to begin with, any noise is a problem and it



doesn’t take a lot of noise to blanket the signal entirely. Such a millivolt signal cannot be transmittedtogether with other signals in a multi-core cable and it cannot be brought to several users in parallel,such as to an indicator and a recorder, although PLC’s with TC input exist.

Though, it is true that in some instances by using thermocouple wires over a long distance andachieving satisfactory results, the odds are against it, making it a risky method to try in a cement plant!

Even the idea to amplify the voltage signal (to reduce the signal to noise ratio) is not good enoughsince the noise picked up may be several hundred volts high.

Engineering / B07 - Eng / C05 - Sensors / Sensors / 5. SIGNAL TRANSMISSION / 5.1 Current output

5.1 Current output

If a thermocouple transmitter with 4-20 mA DC (or 0-20 mA DC) current output is used, instead of avoltage output, some important advantages are gained. The controlled current line eliminates lossesdue to the wire resistance (line losses), because the resistance of the wire merely drops voltage alongthe line - the current remains constant (impressed current). Also, the noise pick-up is all but eliminatedby the very high noise immunity of the current line due to the very low output loop impedance.

This allows to use a twisted pair of ordinary signal wires. The wires are twisted, so that any noise thatappears on the line will be on both lines. It can be eliminated by means of specific electronic circuits atthe input of the upstream connected instrument. (=“common-mode rejection”, meaning the ability of acircuit to reject signals of equal amplitude on both input leads.)

Current signals can be collected in the field (field junction box) and transmitted to the control room withlow-cost multi-core cables.

Summarising, it can be said that the beginning of the measuring range of any type of analoguemeasurement is represented on the transmission line by a current of 4 mA (or 0 mA). The end of themeasuring range of any type of measurement is represented on the transmission line by a current of20 mA. That means, an unscaled value in electrical units is transmitted. To produce an indicationscaled in the desired physical unit the indicator has to be provided with the respective scale.

Engineering / B07 - Eng / C05 - Sensors / Sensors / 5. SIGNAL TRANSMISSION / 5.2 “DEAD ZERO” and “LIVE ZERO”

5.2 “DEAD ZERO” and “LIVE ZERO”

In a standard 0-20 mA the zero-point of the measuring range e.g. 0°C, is represented with 0 mA(“DEAD ZERO”), and the end-point of the measuring range, e.g. 150°C, is represented with 20 mAsignal current. However, the signal current also becomes 0 mA (no current flow), in case of atransmitter failure, broken cable, or loss of power.

In a standard 4-20 mA the zero-point of the measuring range e.g. 0°C is represented with 4 mA (livezero) and the end-point of the measuring range e.g. 150°C with 20 mA. Therefore, for the transmissionof an analogue measurement, only a range of 16 mA is available.

A signal current of 0 mA (no current flow, or a current <4 mA), can only be caused by a transmitterfailure, broken cable or loss of power. Thus, the 2 cases “FAILURE” and “ZERO-POINT ofMEASURING RANGE”, can easily be distinguished.

An electronic circuit can monitor the measurement-loop with “live zero” and immediately generate analarm if a failure occurs.



Engineering / B07 - Eng / C05 - Sensors / Sensors / 5. SIGNAL TRANSMISSION / 5.3 Power supply

5.3 Power supply

A 2-wire transmitter can only operate with a “live zero* standard signal (4-20 mA), because the first 4mA are used to supply the electrical power to the 2-wire transmitter, 4-wire transmitters are availablewith “live zero” (4-20 mA), or “dead zero” (0-20 mA), standard signals.

Engineering / B07 - Eng / C05 - Sensors / Sensors / 5. SIGNAL TRANSMISSION / 5.4 4-wire and 2-wire transmitters

5.4 4-wire and 2-wire transmitters

4-wire transmitters need 2 wires for the transmitter operating power supply and 2 other wires totransmit the output signal to a remote location for indication or other purposes.

2-wire transmitters need 2 wires only to bring the power to the transmitter and to transmit the outputsignal. The basic idea is to use the first 4 mA of the output signal to cover the transmitter’s powerconsumption and the remaining 16 mA for signal transmission.

4-wire transmitters are available for any DC or AC power supply voltage. The output signal is usually astandard signal of 4-20 mA or 0-20 mA DC. The admissible external burden can go up to 3000Ω;however, a typical burden is 500Ω.

“Zero” and “span” are independently adjustable, which facilitates the commissioning and calibration ofa transmitter. To prevent electrical disturbances caused by “earth-loops” only transmitters withgalvanical isolation between power supply, input and output should be applied. Where feasibleinterconnections between measurement loops should be avoided. (See also the chapter “Non-isolatingand isolating transmitters”.)

Summary

Goals and drawbacks of the 4-wire concept:

♦ “Compact transmitter”, i.e. power supply is integrated in the transmitter.

♦ Large variety of power supply voltages possible (220 V, AC, or 110 V AC is already available atmost locations of the plant).

♦ 4-wire transmitters can perform all measuring functions between “very basic” and “very complex”.

♦ Independent “zero” - and “span”-adjustment.

♦ Very high external burden possible.



♦ Output signal 4-20 mA or 0-20 mA possible.

♦ Cabling and installation expensive, due to separate power supply cable.

The 2-wire transmitter converts the input signal to a standard output signal of 4-20 mA and receives itspower from the same 2 wires.

The output signal consists of two components:

♦ The 4 mA component (also called “live zero”), is a constant drain on the remote located powersupply. This current is used to provide operating power to the transmitter.

♦ The second component, 0-16 mA, is a variable drain on the power supply that is proportional to thetransmitter’s input signal, which may represent a temperature, pressure, flow etc.

The sum of these two current components results in a 4-20 mA current that flows in the measurementloop at the transmitter’s output. It is obvious that 2-wire transmitters may operate only with the“live-zero” standard signal 4-20 mA. The typical measurement loop in 2-wire technology shows thepower supply, the transmitter and the receiving elements, such as analogue inputs, indicators,recorders etc., connected in series with the loop.

Usually the power supply is located in a “clean room”, e.g. in the control centre, however, thetransmitter in a dust and water-proof housing is placed “in the field”, next to the detecting point.

2-wire transmitters using the most advanced electronics technology may operate with power supplyvoltages between 12 V, DC and 50 V, DC. The admissible maximum burden connected to the outputloop depends on the power supply voltage.

In the 2-wire mode it is technically impossible to provide independent adjustments for “zero” and“span”. Therefore, calibration and maintenance is slightly more time-consuming and needs moreexperience compared with 4-wire transmitters.

Engineering / B07 - Eng / C05 - Sensors / Sensors / 5. SIGNAL TRANSMISSION / 5.5 Non-isolating and isolating transmitters

5.5 Non-isolating and isolating transmitters

While driving grounding rods into the ground at two points several hundred meters apart andconnecting a voltmeter between them, a voltage difference becomes noticeable.



This potential difference exists between practically any two points along the earth’s surface. From thisresulted voltage problems can cause when trying to measure a process at a remote location.

It is necessary to ground the sensor at the remote site to reduce noise and to protect the equipmentfrom damage caused by lightning. But if grounded thermocouples are used and if it’s tried to groundone side of the transmitter output loop at the control room, the voltage difference between the twopoints will induce an error current along the line, resulting in an erroneous measurement indication or inequipment damage!

To eliminate this “ground loop”, an isolating transmitter can be used. This type of transmitter electricallyisolates the transmitter’s output loop from the sensor signal as well as - in case of a 4-wire transmitter-, from the power supply, and allows to ground both, the sensor and one side of the output loop.

Everybody knows: a transformer can transform only alternating current (AC). Actually, that’s the reasonwhy direct currents (DC) are first converted into AC, then transformed by the transformer and finallyrectified again to obtain DC, reproducing exactly the DC at the module’s input.

Recommendation, Conclusion

♦ The induced error current, caused by the earth potential difference or by lightning, can causeerroneous measurements and equipment damage!

• Do not use non-isolating transmitters!

♦ The galvanical isolation in transmitter and power supply opens the induced error current path!

• Use only isolating transmitters! Galvanic isolation between signals and power supply.

Engineering / B07 - Eng / C05 - Sensors / Sensors / 6. CONTROL, ALARMING AND DISPLAY



6. CONTROL, ALARMING AND DISPLAY

When the signal at the desired location (e.g. central control room) arrives it has to be further treatedeither for display, recording, alarm or control. In a modern cement plant the 4-20 mA are fed directlyinto the Process Station (PS). This is the simplest method since any measurement can be used for anypurpose without any further effort provided a good standard and user software is installed in the PS.How the signal is treated further can be red in chapter “Motor Control”.

Engineering / B07 - Eng / C05 - Sensors / Sensors / 7. MEASUREMENT USED IN THE CEMENT INDUSTRY

7. MEASUREMENT USED IN THE CEMENT INDUSTRY

The cement industry uses in most cases common instruments but faces some cement specificproblems. As shown in the instrument list, the cement industry applies not too many different types ofsensors, respective measuring principles. However the tendency is increasing.

Problems are encountered mainly with high temperature, clogging and coating. Many of theseproblems can be evaded by selecting the proper instrument, respectively primary element and/orpicking a suitable location. Maintenance and regular calibration avoid break downs and prolong thelifetime of the primary element.

Note: To facilitate easy maintenance, accessibility of the primary elements and thetransmitter is vital.

Cement specific sensors and measuring systems are illustrated in the nextchapters.

Engineering / B07 - Eng / C05 - Sensors / Sensors / 7. MEASUREMENT USED IN THE CEMENT INDUSTRY / 7.1 Temperature

7.1 Temperature

In the cement industry generally thermocouples, PT 100 resistance bulbs and pyrometers are used.For kiln shell measurement, temperature scanners are often applied together with a display system.These scanner systems range from a simple pyrometer connected to a recorder or from a scannerhead connected to a PC with an elaborated software giving information about the shell temperature,interpretation about the inside of the kiln and even a brick management and slip detection can beincluded.

Engineering / B07 - Eng / C05 - Sensors / Sensors / 7. MEASUREMENT USED IN THE CEMENT INDUSTRY / 7.1 Temperature / 7.1.1Thermocouple

7.1.1 Thermocouple

Mostly applied for temperature measurement in the cement industry are thermocouples which use thepeltier effect as measurement principle. A thermocouple consists of two dissimilar metals. Betweenthese metals a voltage is generated. The electro-motoric force (emf) developed by a thermocoupledepends on the temperature of both, the measuring (hot) junction and the reference (cold) junction.

Important for a thermocouple is therefore:

♦ the type of thermocouple and the manufactures data (e.g. type K thermocouple)



♦ the extension cable of the appropriate type (e.g. type K for type K thermocouple)

♦ temperature range and type of thermocouple (e.g. type K for 200 - 1200°C)

♦ cold junction reference temperature 0°C, 20°C or others.

♦ the type of protection sheath. The length of the TC as well as the protection tube should bestandardised (e.g. 800 mm and 1200 mm). The material for the sheath may however be differentfor various applications since a high temperature protection sheath is very expensive.

To calibrate a transmitter for a thermocouple, a mV source is required. This source is connected in themeasuring loop instead of the thermocouple. According the manufacturer's data sheet, mV for 0°C andmV for the maximum temperature are fed into the loop. Then the output of the transmitter 0°C = 4 mAand max. temperature = 20 mA are checked as well as the display in the control room together withany alarm limits. The temperature range from -200°C up to +2000°C can be covered withthermocouples.

Engineering / B07 - Eng / C05 - Sensors / Sensors / 7. MEASUREMENT USED IN THE CEMENT INDUSTRY / 7.1 Temperature / 7.1.2Resistance bulb RTD PT 100

7.1.2 Resistance bulb RTD PT 100

For lower temperature (e.g. for machine protection) resistance thermometers are used. RTD’s work onthe principle of a resistance changing when the temperature varies. Mostly used in the cement industryis the Pt 100 platinum resistance bulb. The PT 100 has a resistance of 100Ω at 0°C and 158.8Ω at150°C. When selecting a resistance bulb, it is important to specify a 2-, 3- or even a 4-wire type. Tocompensate for the line resistance a 3-wire type normally is sufficient. If the transmitter is installednearby, even a 2-wire bulb is good enough.

To calibrate a transmitter for a PT 100 a resistance decade is required. This resistance box isconnected in the measuring loop instead of the PT 100. According the data sheet the base resistance(e.g. 100Ω for PT 100) for 0°C and the maximum resistance for the maximum temperature (e.g.158.8Ω for PT 100) are fed into the loop. Then the output of the transmitter 0°C = 4 mA and max.temperature = 20 mA are checked as well as the display in the control room together with any alarmlimits. PT 100 transmitters require initial calibrations of the entire loop. After that only an occasionalcheck up is required. With PT 100 bulbs temperatures from -250°C up to +1000°C are measurable.

Engineering / B07 - Eng / C05 - Sensors / Sensors / 7. MEASUREMENT USED IN THE CEMENT INDUSTRY / 7.1 Temperature / 7.1.3Pyrometer

7.1.3 Pyrometer



The cement industry uses two types of pyrometers. The radiation pyrometer which detects radiationthrough an optical lens system onto the thermopile or photo cell and the two colour ratio pyrometerwhich compares the ratio of the radiation intensity of two different wave lengths.

Engineering / B07 - Eng / C05 - Sensors / Sensors / 7. MEASUREMENT USED IN THE CEMENT INDUSTRY / 7.1 Temperature / 7.1.4Scanner

7.1.4 Scanner

The central feature of a scanner is a motor driven optical system which scans the entire kiln with acertain frequency (e.g. 16 Hz). The front of the scanner measures parallel along the axis of the kiln, inthe back of the scanner a reference temperature is used to calibrate the system.

Engineering / B07 - Eng / C05 - Sensors / Sensors / 7. MEASUREMENT USED IN THE CEMENT INDUSTRY / 7.2 Pressure

7.2 Pressure

Pressure can be measured either as liquid column (e.g. U-tube) with a mechanical principle (e.g.diaphragm, burden tube) or electrically (e.g. piezo crystal, strain gauge). The pressure measured in thecement industry is usually very low. Therefore, the differential pressure (gage pressure that is thedifference between the absolute pressure and the atmosphere) is measured. Most pressuretransmitters applied in the cement industry are of the mechanical type where one side is connected tothe process and the other side is left open to the atmosphere.

Drawing F44570-1 is a typical example of a differential pressure measurement. The bellows aresubjected to a pressure change and move, via mechanical links, a plunger in an electrical field. Theelectronic senses the movement and converts the change in the field into an electrical standard signal.

To avoid problems with pressure transmitters some installation points have to be observed:

Location: locate the transmitter near the pressure tapping easyaccessible. Mostly applied as unit by the manufacturer.

Process line: the pressure tapping can be above or below the transmitter.In any case the process line must be installed such that nowater or dirt can accumulate. Thus, always have at least 2%slope in the process line. If the tapping is above thetransmitter a water trap is required.

Tapping: install a tapping in such a way that cleaning is easilypossible. Thus, a simple removable cover should allowpocking of the process tapping.

In large ducts two or more tappings connected with eachother give a better result.

To calibrate a pressure transmitter a pressure source is required. This source is connected in themeasuring loop on the primary side of the transmitter. To check the zero both sides of the transmitterare left open to the atmosphere. To check the maximum, an equivalent pressure (or vacuum) isapplied. The output of the transmitter 0 kPa = 4 mA and max. pressure = 20 mA are checked as wellas the display in the control room together with any alarm limits.



Engineering / B07 - Eng / C05 - Sensors / Sensors / 7. MEASUREMENT USED IN THE CEMENT INDUSTRY / 7.3 Flow (gas andliquids)

7.3 Flow (gas and liquids)

Flow measurement is thoroughly discussed in the corresponding paper of the process technologydepartment.

Engineering / B07 - Eng / C05 - Sensors / Sensors / 7. MEASUREMENT USED IN THE CEMENT INDUSTRY / 7.4 Level

7.4 Level

Level measurements, whether continuous or just as level alarms are often applied and often not 100%satisfactory. A poll carried out in 1992 querying the performance of the different level measurements insome 30 factories showed results from very satisfactory to useless. Depending on the method applied,the installation and the maintenance the same level measurement is rated different with regards toperformance. The following level measurements are used successfully in the cement industry. Somemechanical types like paddle, ball etc. are not explained since their function is very simple.

Engineering / B07 - Eng / C05 - Sensors / Sensors / 7. MEASUREMENT USED IN THE CEMENT INDUSTRY / 7.4 Level / 7.4.1 Capacityprobe

7.4.1 Capacity probe

The capacity probe uses the measuring principle of two plates being isolated by a dielectricum ε wherethe capacitance depends on the area of the plates, the distance between the plates and the mediumbetween the plates the dielectricum. When installing a capacity probe, the plates (the probe and thesilo wall) are fixed and the distance is fix provided, the probe is mounted properly. The variation in themeasuring loop is therefore the dielectricum ε which is formed either by material between probe andwall or air. The following problems may occur thus hampering the performance:

♦ sticky material on the probe. This can be avoided using the proper type of level probe that isinsulated or partly insulated probes.

♦ probe installed too close to silo wall thus evoking bridging.

♦ sensitivity adjusted to fine. Humidity in the air or in the material changes the property of thedielectricum.

♦ mechanical damage may result from coarse material or from sheer force. (E.g. coal dust has veryhigh sheer force). Use an other measuring principle or use an insulated capacity probe.

Engineering / B07 - Eng / C05 - Sensors / Sensors / 7. MEASUREMENT USED IN THE CEMENT INDUSTRY / 7.4 Level / 7.4.2 Vibration

7.4.2 Vibration

The vibration fork level probe is only used for a single point measurement. A driver induces a vibrationin the probe and a controller senses a change when material dampens the vibration. The tuning fork isobtainable in two forms, one being the actual fork and the other in form of a tube. The followingproblems may occur thus hampering the performance:

♦ material stuck between the fork. Use a tube type to avoid this problem mostly occurring with coarsematerial.

♦ material coating the probe. Use the fork type probe since this problem takes place mainly with finematerial.



Engineering / B07 - Eng / C05 - Sensors / Sensors / 7. MEASUREMENT USED IN THE CEMENT INDUSTRY / 7.4 Level / 7.4.3 Electromechanical

7.4.3 Electro mechanical

Quite successful practice is the level measurement with the so called silo pilot. A rope or measuringtape connected to a weight is lowered into the silo. As soon as the weight touches the material surface,the rope (tape) tension ceases, the motor reverses and pulls the weight back into its original position.During the upward travel the tape is measured, such giving an indication of the level within the silo. Thefollowing points have to be considered by using a silo pilot:

♦ position on top of the silo so that no material can fall onto the weight. When lowering the weight itshould be in the centre of the material cone.

♦ access to the rope respective belt and the weight must be easy. Install an inspection door to assistmaintenance.

♦ select the proper weight for the corresponding material

Engineering / B07 - Eng / C05 - Sensors / Sensors / 7. MEASUREMENT USED IN THE CEMENT INDUSTRY / 7.4 Level / 7.4.4Contactless level probes

7.4.4 Contactless level probes

Several methods allow level measurement without being in contact with the material. Ultra sonic is themost popular and is used with coarse material, e.g. gypsum, limestone. In connection with dust in thesonic beam or on the material surface <40°C, e.g. cement, raw meal, this method should not beapplied. Level can be measured up to 45 m under good conditions. Rather new on the market areinfrared and radar. With infrared no experience has been gained. Good experiences have been gainedwith radar in environment where ultrasonic fails. In clinker and in raw material silos the measurementwith radar proved to be successful even with high dust load. In raw meal the measurement did not workand the problem seems to be the conductivity. Only material with a certain conductivity respective a lowdielectricum can reflect the radar beam. Up to now only measurements for 35 m depth are available.This is due to the strength of the source which must be within the limit of the wireless regulation of therespective country. The radar method works in a temperature range of -40°C up to +250°C.

Engineering / B07 - Eng / C05 - Sensors / Sensors / 7. MEASUREMENT USED IN THE CEMENT INDUSTRY / 7.4 Level / 7.4.5Radiation level probes

7.4.5 Radiation level probes

Well-known and well-proven are the nuclear type of level probes. From a measurement technical pointof view no restrictions are known. In most cases where all other methods fail the nuclear level probeserves well almost maintenance free. In many countries, however, importing or handling the source isvery difficult. Additionally the disposal of the source is in many cases almost impossible and requires alot of responsibility of the person in charge. And more restriction for the future are to be expected.

An alternative (even in the pre-heater cyclones) offers the micro wave level measurement. Thearrangement is similar to the nuclear level measurement a microwave source on the one side and adetector on the other side. The microwaves beam of approx. 20o angle, some 5.8 GHz or as high as24.125 GHz penetrates any non-conductive material. The maximum distance through air is around 8m.

Alternative measurements around the corner are possible if the space is limited. The installation mustbe such that a light beam would be properly reflected.



Microwave level measurements are sensitive to moisture. In fact, microwave is used as well formoisture measurement. The microwave source is so weak, that no danger comes from themeasurement. (No cooking can be done with this microwave source, the energy emitted is less than 25mW.)

Engineering / B07 - Eng / C05 - Sensors / Sensors / 7. MEASUREMENT USED IN THE CEMENT INDUSTRY / 7.5 Weighing

7.5 Weighing

Weighing and weigh feeder play an important role in the cement industry. To produce a good cementquality, accurate weigh feeding of the different components is important. To bill the customeragreeable again, weighing plays the key role. Already these two important requirements show that forweighing two different ways are possible: the static weighing (weigh bridge) and the dynamic weighing(weigh feeder).

The weigh bridge at the factory entrance is regarded as the most important and accurate unit. Theweigh bridge is in many countries subjected to stringent government regulation and must be checkedand calibrated on a regular base. For weigh bridges the measuring principle applied is usually one orseveral load cells. Due to the strict government roles and due to the simple measurement principlethese scales usually are fairly accurate.

Small bins are as well placed onto load cells to weigh the contents. And, as long as the construction issuitable, that is three load cells, free moving construction and protection against wind, themeasurement can be very accurate. The total weight (xy tons in the bin) may not be accurate but lossin weight is accurate. Thus, for calibration of a weigh feeder or for volumetric weigh feeding a loss inweight is well-qualified.

The next important weighing principle is the continuous measurement of material to constantly feed anaccurate amount of material, the dynamic weighing with weigh feeder. Several principles are appliedwith different accuracy, different efforts for maintenance and different prices.

Thus when selecting the weigh feeder the following points must be taken into consideration:

♦ Accuracy required.

♦ Mechanical suitability for the material and the environment.

♦ Space availability (height and area). Especially building height can be reduced (cost saving) withcertain weighing arrangements and weighing principles.



♦ Signal availability and signal transmission. (4-20 mA and digital signals or communication via a bussystem).

♦ Maintenance that is time interval between calibration, access for calibration e.g. re-routing ofmaterial onto a lorry, cleaning required, complexity of the control, spare parts etc.

♦ Measurement principle.

♦ Silo discharge system. Most problems of inaccurate weighing arise from poor flowing material.

Engineering / B07 - Eng / C05 - Sensors / Sensors / 7. MEASUREMENT USED IN THE CEMENT INDUSTRY / 7.5 Weighing / 7.5.1 Beltweigher

7.5.1 Belt weigher

The most common measuring principle applied in the cement industry is the belt weigher. A section ofthe belt runs over idlers supported by a frame section placed onto load cells.

The weight over this belt section multiplied with the speed represents the feed rate Q = P * v whereas:

Q = feed rate [t/h]

P = weight per width [kg/m]

v = speed [m/h]

This principle is well-known and if maintained properly very accurate (error < 1%)

Also different methods of calibration are offered, but only the following are accurate and repeatable:Run for e.g. 5 minutes material onto a lorry, weigh the lorry and calculate the feed rate weight x 12 (ifthe calibration time was 5 min.). Thus when designing the weigh feeders a means to calibrate onto alorry must be included or alternatively weigh bins above the feeders to calibrate with the loss in weightmethod which is a very accurate method too.

Engineering / B07 - Eng / C05 - Sensors / Sensors / 7. MEASUREMENT USED IN THE CEMENT INDUSTRY / 7.5 Weighing / 7.5.2Gravimetric feed system

7.5.2 Gravimetric feed system

A gravimetric feed system is mainly used for coal feeders. This weighing system is complex butaccurate. A bin on load cells is rapidly charge with material. The filling then stops and for n seconds thebin is emptied. (tn = discharge time depending on bin size).



When reaching a certain low level the bin is recharged again and during this time the speed of thedischarge feeder is maintained at the previous feed rate. The feed rate Q is calculated by the formula:

Q =

m = loss of weight during tn [kg]tn = discharge time [s]

Modern systems calculate the feed rate during a very short time period and take the whole time tocalibrate the system. The accuracy of such a system is < 1%. The maintenance however is high andthe system is complex.

Engineering / B07 - Eng / C05 - Sensors / Sensors / 7. MEASUREMENT USED IN THE CEMENT INDUSTRY / 7.5 Weighing / 7.5.3Volumetric feeders

7.5.3 Volumetric feeders

A simple method is a volumetric feeder. The accuracy is largely dependent on the feeder itself and onthe flow property of the material. Depending on the required accuracy, a periodic calibration onto alorry is needed. If a higher accuracy is required a weigh bin has to be introduced prior to the feeder anda similar measuring method as mentioned in the gravimetric flow measurement has to be applied.

Engineering / B07 - Eng / C05 - Sensors / Sensors / 7. MEASUREMENT USED IN THE CEMENT INDUSTRY / 7.5 Weighing / 7.5.4Impact flow meter

7.5.4 Impact flow meter

A controversial measurement is the weight measurement with an impact flow meter. Material flows onto a plate which in turn is placed on a load cell. The impact on to the plate is proportional to the impact



created by a mass falling from a height h. The impact is in practice also depending on the flowproperties of the material which in turn is depending on various factors. Thus, this measurementrequires a fair amount of mechanical design around the actual measurement. Dedusting, the feed toand away from the impact flow meter are crucial for the accuracy of the measurement.

In practice the impact flow meter is mostly applied together with a pre bin arranged with load cells. Thisarrangement allows an automatically periodical calibration of the flow meter, in order to compensatesticking material at the plate.

Engineering / B07 - Eng / C05 - Sensors / Sensors / 7. MEASUREMENT USED IN THE CEMENT INDUSTRY / 7.5 Weighing / 7.5.5Nuclear weigh feeder

7.5.5 Nuclear weigh feeder

Weighing with nuclear weigher is nothing new in the cement industry but is and remains a controversialmeasurement. Although, a simple and reliable measurement the import and the disposal of the nuclearsource is problem. A nuclear weigher consists of a gamma source and a gamma ray detector. Both areconnected on a mechanical frame which is located across the conveyor. The beauty is that almost anyconveyor (e.g. belt, apron feeder, screw conveyor etc.) can be fitted with an A or C frame nuclearweigher. Even in an existing installation does the installation of an A or C frame seldom present aproblem.

A nuclear weigh feeder determines the weight by measuring the absorption of the material. Everymaterial absorbs radiation according the exponential law. The absorption is proportional to thethickness and the density of the material bed. The absorption is then related to the mass of thematerial which, when multiplied with the speed, results in the mass flow.

The main absorption (basic absorption Ag) is in many cases given by the construction. The absorptionwith a given density is then proportional with the bed thickness (Am). To receive good results theabsorption Ag should not be larger than 95%.



Due to a less thick material bed (3) the absorption measured by the detector (5) is lower. Theabsorption (2) by the conveyor (4) is remaining constant and calibrated as zero.

When installing an nuclear weigher the following points should be taken into consideration:

♦ import regulation for nuclear devices

♦ disposal of nuclear sources

♦ building and conveyor construction

♦ basic absorption (Ag)

♦ electronic with source decay compensation

♦ even material flow (an irregular bed which influences the measurement negatively)

♦ the initial accuracy is around 2% remaining constant even with hardly any maintenance.

Engineering / B07 - Eng / C05 - Sensors / Sensors / 7. MEASUREMENT USED IN THE CEMENT INDUSTRY / 7.5 Weighing / 7.5.6 Headflow meter

7.5.6 Head flow meter

In an air lift the air pressure measured is more or less proportional to the amount of materialtransported. However, pressure influence other than the amount of material is coming from dedustingand from pressure changes from the system following the air lift (e.g. pre-heater and kiln). The headflow meter as an indication to the material flow is quite acceptable.

Engineering / B07 - Eng / C05 - Sensors / Sensors / 7. MEASUREMENT USED IN THE CEMENT INDUSTRY / 7.6 Analyticalmeasurements

7.6 Analytical measurements

For further information, please refer to the appropriate paper “Quality assurance” in the materialtechnology II.

Engineering / B07 - Eng / C05 - Sensors / Sensors / 7. MEASUREMENT USED IN THE CEMENT INDUSTRY / 7.7 Electrical energy andpower measurements

7.7 Electrical energy and power measurements

Engineering / B07 - Eng / C05 - Sensors / Sensors / 7. MEASUREMENT USED IN THE CEMENT INDUSTRY / 7.7 Electrical energy and



power measurements / 7.7.1 Introduction

7.7.1 Introduction

In the cement industry, the topic “Energy” will become more and more important. - In the past untiltoday the price for electrical energy is still low enough that nobody cares to much. But the near futurewill show us the opposite. The energy consumption will still increase but the energy production cannotfollow this rising demand. Thus a bottle-neck will occur. The power companies have already started tothink about increasing energy prices and how to introduce new tariff structures (Energy Exchange).Consequently, we have at least to stabilise our energy consumption or, even better, decrease theconsumption. The first step will be to measure before other steps can be taken. - The followingchapter treats this topic.

Engineering / B07 - Eng / C05 - Sensors / Sensors / 7. MEASUREMENT USED IN THE CEMENT INDUSTRY / 7.7 Electrical energy andpower measurements / 7.7.2 Definition of energy and power

7.7.2 Definition of energy and power

What is electrical energy?

Energy, generally, is stored work or the ability to perform work. Electric energy (Wel) is potential energyor expressed in an other way, the product of electric voltage (U) and electric charge (Q). The electriccharge can be replaced by the product of current and time (Wel = U * Q = U * I * t; whereas I = currentand t = time). The electric energy is comparable to energy of position in the mechanic that is:

♦ potential difference: height -> voltage U.

♦ quantity: weight -> electric charge Q.

The unit is volt-ampere-second [VAs] or in a more practical way kilo-watt-hour [kWh]. One kWh isequal to 3.6 MJ [860 kcal].

What is electric power?

To express performance the work to complete is related to the time required to do it. Similar, the morepowerful a machine is, the more work can be done in a shorter time.

Thus, the power is proportional to the work and inverse proportional to the time to complete the job.The electric power (P) is the product of voltage (U) and current (I). At the first sight, there is no timeany more in the formula, but the definition of the current is the relation between the transported chargequantity and the time. The electric power is comparable to the mechanical power. For example, thepower of a hydro power plant is dependent on the height of fall (voltage) and the flux (current). - Theunit is volt-ampere [VA] or more practical kilo-watt [kW].

Apparent, actual, reactance

The power companies bill in most cases the actual energy only. To avoid producing too much apparentenergy, they demand a power factor correction between 0.87 and up to 0.9. Few power companies askfor a reactance energy meter and if certain values are surpassed adjust the bill accordingly. Somepower companies bill the client already according the apparent energy (measured actual and reactiveenergy). And this may be the future method of accounting the client since a power company has toproduce the apparent power and not only the actual power.

Using a mechanical diagram the three electrical components: apparent (resultant), actual (linear) andreactive (lateral) are explained.

The following picture explains the three different electrical components, apparent, actual and reactivecurrent. Whether current, power or energy is used is immaterial for this example.



When looking at the force diagram the energy required to pull the spring is obviously the linear force Fp(electrical actual force). The spring is subjected to the following two forces:

♦ The lateral force FQ (electrically reactive force) which is not required.

♦ The resultant force F (electrically apparent force) has to be produced in order to gain sufficientmomentum to pull the spring apart.

When measuring an electric circuit with a transducer the actual power is measured which is required todrive a machine. The power company in turn produces the apparent power. If the cosine ϕ is multipliedwith the apparent power, the result is the actual power. The difference between the produced and theconsumed power is the reactive power.

Apparent power S = U * I [VA] or [kVA]

Actual power P = U * I * cos ϕP = S * cos ϕ

[W] or [kW]

Reactive power Q = U * I * sin ϕ [var] or [kvar]

Why measure?

As already mentioned, Electrical Energy centributes 20-30 % of the cement production cost. Thuselectric energy is important factor as a production component in the cement industry. It is thereforeimperative to measure the energy consumption in order to be able to determine solutions to saveenergy and thus maintaining the costs at least at the present level.



The energy consumption [kWh] and the specific energy consumption [kWh/t] are even units tocompare for example departments in different plants or different types of machines (e.g. ballmill/vertical mill) to each other.

Where to measure?

Drawing E310015 shows the process structure in a cement plant which is ideally represented with thecorresponding electrical structure and thus the ideal energy measuring points.

The measuring points are arranged in different levels:

♦ Main entrance-level; measuring point for charging by power company

At this point, the local power company measures the total consumption of the plant; it should also be acomparable-measuring of the plant; but attention, the result has not to be the same (two measuringcircuits).

♦ Department-level;

♦ Every department should be measured separately to have an overview of the electric consumptionin the different departments. Likewise for large consumers which are directly connected to themedium voltage distribution.

♦ Process/Non-process-level;It is necessary to measure the non-process part to distinguish between process- andnon-process-consumers. Since less measuring points are used for non-process measurement,costs can be reduced by measuring the

♦ Total - non-process = process. (see drawing E310015)

♦ Special consumer-level; This level contains consumers of special interest from an energy point of view.

Energy-/power metering in a cement plant

If all these measuring points are counted together, the total will be around 50. But in practice it is verydifficult to find such an electric distribution. So in reality the amount of measuring points will increase to500 points which will be rather costly. The conclusion is, that measuring starts with proper electricaldepartments thus a proper distribution.

How to measure energy?

Today there are two measurement principles for electric energy, a direct measuring method and anindirect one. - An important criterion is the measuring principle. The method applied depends on the



kind of load, the connected voltage (voltage - and/or current transformer necessary) and the accuracyrequired. The figure F44942 shows different connection diagrams for the measuring method withkWh-meter. The same principle is utilised for a power transducer.

kWh-meter (direct measuring method)

The kWh-meter forms with the current-path and the voltage-path a mechanical torque, which isproportional to the electric power. This torque sets the metering disc in a corresponding number ofturns per unit of time. The multiplication with the time to receive energy, follows with the addition of thenumber of rotations. The kWh-meter shall be equipped with an on/off output module. This moduleincludes a pulse contact system and a pulse amplifier, suitable for further handling in a control system.For example; In the control system, the energy will be calculated with the time between two pulses.The practice shows that this “digital” method is not such exact than the method described below. - Theabove described measuring method is the principle of “Ferraris”-counter or eddy current motor.

Today more and more static kWh-meters are utilised. The same measuring method is done in anelectronic way and not any more in an electro mechanical way, but there is still a pulse contact output.

Power transducer (indirect measuring method)

The power transducer measures current and voltage separately and calculates internally the electricpower. The output signal is an analogue signal (4-20 mA) for electric power. This analogue signal is aninput in the control system where the signal is integrated with the time which results in a more accuratemeasurement as opposed to a pulse-signal from a kWh-meter.

Process measurement display

The display of the energy measurement is just as important as the measurement itself. Themeasurement has to be displayed in form of power or energy as well as specific energy measurement(e.g. for the raw mill → kWh per ton of raw meal. The display is further described in chapter “MMI,Visualisation”.

Engineering / B07 - Eng / C05 - Sensors / Sensors / 7. MEASUREMENT USED IN THE CEMENT INDUSTRY / 7.8 Field devices

7.8 Field devices

Just as important as analogue instruments are the on/off sensors, control and field devices. Mostmeasuring principles as described in the previous sections are available as on/off devices. Few on/offsensors are available as smart sensors and even less can be connected to a bus (Profibus). Theproblems encountered with field devices are similar as with analogue instruments and the sameprovision has to be made as with the analogue instruments. Sensors like limit switches, pressureswitches, speed switches etc. are available in different price classes. Do not feel tempted to buy cheap



sensors as the money saved will be spent tenfold on maintenance and on down time. Only the best isgood enough. And only the best installation will give acceptable performance. And where possiblereplace on/off sensors with analogue sensors.



Engineering / B07 - Eng / C06 - Motor Control

C06 - Motor Control



Engineering / B07 - Eng / C06 - Motor Control / Motor Control

Motor ControlRoland Luder

1. INTRODUCTION

2. PROGRAMMABLE CONTROLLERS (PLC)

2.1 Introduction, History

2.2 Hardware of Programmable Controllers

2.3 Structure of a PLC

2.4 Software of Programmable Controllers

2.5 Programming a PLC

2.6 Criteria governing the Choice of PLC



Engineering / B07 - Eng / C06 - Motor Control / Motor Control / 1. INTRODUCTION

1. INTRODUCTION

As already mentioned in the chapter AUTOMATION SYSTEMS, Motor Control is a very important partof cement plant control. It is the part which switches drives and valves etc. ON and OFF.

These switching operations have to be performed under normal as well as under special operatingconditions of the process. Motor control further includes monitoring and alarming of these conditions.Physically, a motor control system consists of

♦ an operating panel as interface to the operator (with push buttons, lamps, mouse, displays)

♦ a logic controller which performs the logical interlocking of all information (with relays, electronic orprogrammable controllers)

♦ a plant/process interface with sensors and command elements (switches, contactors, valves)

♦ cabling, which interconnects the different components of the system.

A motor control system for a modern cement production line has to control approx. 1000 motors and afew hundred valves, heaters, acoustic and optical devices. The correct and efficient command of allthese items requires a systematic planning of the system and a careful selection of the components.

The tendency in systems design is to integrate motor control and analogue control functions into thesame physical unit. This set-up has the advantage that only one type of hardware is required and thatinterconnections between the binary and the analogue systems can be programmed and do not haveto be wired.

Engineering / B07 - Eng / C06 - Motor Control / Motor Control / 2. PROGRAMMABLE CONTROLLERS (PLC)

2. PROGRAMMABLE CONTROLLERS (PLC)

Engineering / B07 - Eng / C06 - Motor Control / Motor Control / 2. PROGRAMMABLE CONTROLLERS (PLC) / 2.1 Introduction,History

2.1 Introduction, History

The logic controller is the brain of the motor control system, i.e. the decision-making part. It takes careof the safe, convenient sequential starting, running and stopping of single motors or of whole groups ofmachines.

There are basically three different techniques to build-up an electrical logic controller:

Engineering / B07 - Eng / C06 - Motor Control / Motor Control / 2. PROGRAMMABLE CONTROLLERS (PLC) / 2.1 Introduction,History / 2.1.1 Relay Technology

2.1.1 Relay Technology

A relay uses the electro-mechanical equipment which uses the electromagnetic force of an electricalcoil to open or close electrical contacts. The internal wiring of these coils and contacts determines thespecific function of the set-up.

Relays control has been the only technology until approx. 1960.

Today relays are still used for interfacing (power amplifying) purposes and for very small control



systems.

Engineering / B07 - Eng / C06 - Motor Control / Motor Control / 2. PROGRAMMABLE CONTROLLERS (PLC) / 2.1 Introduction,History / 2.1.2 Electronic Card System

2.1.2 Electronic Card System

This technology was developed in Europe and was applied approx. until 1975. It consists of electroniccomponents, pre-assembled on printed circuit boards and performing specific logic functions. Thefunction of the total system is determined by the wiring between the different logic cards.

Today these systems are hardly anymore installed.

Engineering / B07 - Eng / C06 - Motor Control / Motor Control / 2. PROGRAMMABLE CONTROLLERS (PLC) / 2.1 Introduction,History / 2.1.3 Programmable Controllers

2.1.3 Programmable Controllers

This technology was introduced in the market approx. 1970, and is the today’s dominating technology.The tendency is to replace relays by programmable controllers even in very small applications. Theprogrammable controller uses basically the same idea as a computer does: it uses a memory to storeinformation and it uses this information to execute step by step a procedure which is determined by thisinformation (program; software).

The advantages of the programmable controllers as opposed to other technologies are:

♦ No mechanical wear

♦ no rewiring when modifications are required

♦ easier planning (hardware / software can be planned in parallel)

♦ higher level of automation is possible

♦ integrated solutions with analogue control and data acquisition are possible.

Engineering / B07 - Eng / C06 - Motor Control / Motor Control / 2. PROGRAMMABLE CONTROLLERS (PLC) / 2.2 Hardware ofProgrammable Controllers

2.2 Hardware of Programmable Controllers

A programmable controller is basically a ‘BLACK BOX’ with INPUTS and OUTPUTS and a connectionto a PROGRAMMING UNIT.

With the programming unit, the user determines how the different inputs and outputs must be logicallycorrelated and sequenced to perform the desired control task. The programming nowadays uses a PCto display, to enter or to modify the program as well as an additional storage devices to safeguard it.

The ‘BLACK BOX’ is composed on one or several chassis or racks which basically contain thefollowing elements (see Fig. 2.2.1)

Figure 2.2.1 Programmable ControllerHardware Configuration



1) Power supplyTo provide the internal stabilised control voltages of the programmable controller

2) ProcessorTo perform the actual logic / timing and internal control functions

3) MemoryTo store the program and data

4) Communication portTo communicate with external devices (as programming panel, computer, other programmablecontrollers) or with remote input/output devices.

5) Input/Output (I/O) DevicesTo transform the signal coming in (INPUT) from outside (e.g. from a level switch) or going out(OUTPUT) to the outside (e.g. to lamps, to the MCC). Today most programmable controllershandle as well analogue I/O signals.

Physically all these elements are generally grouped on one or several cards of the draw-out type. Thecards are internally interconnected via a system bus which performs a fast exchange of the necessaryinformation between the different cards.

This arrangement provides great flexibility in hardware planning: if additional memory space isrequired, for examples, it is generally sufficient to plug in an additional memory card. The draw-outtechnique, of course, also simplifies troubleshooting of the hardware (defective card out - new card in -restart). It must be noted, however, that once a system is correctly set-up, there are generally no morehardware failures.

Figure 2.2.2 shows an example of an input card of the draw-out type which contains 16 inputs. Outputcards may be arranged in a similar way.

Figure 2.2.2: INPUT (OUTPUT) Card of a Programmable Controller



The size of a programmable controller can be expressed by different figures. The most important figureis the number of I/O which a programmable controller can handle. The smallest units start at approx.15 I/O, the biggest go up to 8000 I/O.

The maximum memory size is another key figure which, however, generally goes in parallel with thenumber of I/Os. Normal sizes range from approx. 0.5 K up to 1000 K (1 K = approx. 1000 programsteps).

The cycle time (see ‘software’) generally goes in parallel with the size of the memory used and isgenerally expressed in ms/1 K. It ranges from approx. 0.5 to 50 ms/1 K.

Engineering / B07 - Eng / C06 - Motor Control / Motor Control / 2. PROGRAMMABLE CONTROLLERS (PLC) / 2.3 Structure of a PLC

2.3 Structure of a PLC

The diagram below shows the structure of a PLC. The main functional elements of a programmablelogic controller are the control unit with one, or sometimes several micro-processors and thecorresponding memories for data (timers, counters, markers, etc.) and programs (programmablememories).

Block diagram of programmable controller

The program memory, processor, counter, data memory and the input/output units are interconnected.Here connection via bus has become standard practice. By means of this bus the data are exchangedbetween data memory, processor and program memory.

Engineering / B07 - Eng / C06 - Motor Control / Motor Control / 2. PROGRAMMABLE CONTROLLERS (PLC) / 2.3 Structure of a PLC /2.3.1 Differences between PLC and a Computer



2.3.1 Differences between PLC and a Computer

What are the main differences? In a PLC so-called bit processing is used. This is special processingmethod which processes only one bit. In contrast, the computer always uses word processors, i.e.single bits can only be addressed by programming.

A PLC functions in much the same way as a computer, but with the following main differences.

♦ User’s programs are executed cyclically

♦ A PLC needs a very simple operating system

♦ The information is processed a bit at a time (facilities for word processing are available)

♦ A PLC is a real-time system, i.e. the results of operations are obtained within a short, clearlydefined time

♦ The set of command is especially intended for control requirements and is therefore limited in itsscope

♦ The hardware is designed for rough industrial conditions (temperatures between -10 and +60°C)

♦ Programming is simple, can be understood by electricians and is easy to learn

♦ Addressing of input and output cards is transparent

♦ To program a PLC a special programming unit has to be connected to it.

Engineering / B07 - Eng / C06 - Motor Control / Motor Control / 2. PROGRAMMABLE CONTROLLERS (PLC) / 2.4 Software ofProgrammable Controllers

2.4 Software of Programmable Controllers

In the chapter ‘Hardware of Programmable Controllers’ we have seen that a programmable controllercan be represented as a ‘BLACK BOX’ which contains inputs and outputs.

The different inputs and outputs have now to be logically and sequentially interconnected to performthe desired control task. To represent this "logical and sequential interconnection", special languageshave been elaborated. Unfortunately, these languages or graphic presentations are not standardised.Main differences can be found between European and American presentations but even within onelanguage, practically every suppliers uses his own ‘slang’.

For a long time there was a certain market tendency toward the ladder diagram, influenced by theAmerican market where generally only this language is used.

The ladder diagram is based on the representation which was used for relay systems. It can, therefore,easily be learned by people who worked with those systems but it does not well represent the newthinking in inputs/outputs.

Nowadays a standard is on the market named IEC1131.

Any logic can actually be represented with only 4 different instructions:

Logic AND, logic OR, logic NOT and TIME instruction. In order to make programming easier, allprogrammable controllers use additional logic instructions which are composed of specific often-usedcombinations of above four elements.

When a programmable controller is equipped to accept analogue inputs, additional instructions forarithmetic operations and file handling are available.



For bigger applications (as e.g. in the cement industry) a structured programming making use of‘macros’ or subroutines should be applied. The same applies when analogue control capabilities areincluded in the programmable controller.

The actual program is now composed of a series of program steps, every step uses a combination ofinstructions or ‘macros’ to define how the different inputs have to be linked with the outputs.

It is important to mention that the program is executed step by step. This means that one instructionafter the other is read, interpreted and executed.

At the end, the program automatically restarts at the beginning. The total time which a program needsto come once from the beginning to the end is called the system cycle time. This time is generally veryshort (approx. 1...300 ms). For an external observer of the system it, therefore, behaves as ifeverything (all commands) would be immediately executed - all at the same time. In reality, asexplained, only one instruction is executed at one time.

Engineering / B07 - Eng / C06 - Motor Control / Motor Control / 2. PROGRAMMABLE CONTROLLERS (PLC) / 2.5 Programming a PLC

2.5 Programming a PLC

In order to program a PLC a special programming unit is required. The pictures below show differentversions of programming units.

Programming units are very efficient, they are PC's of special industrial design, equipped withlarge-area LCD or with a monitor. They can translate the functions entered by the user in a higher-levelprogramming language specifically intended for control tasks, e.g. as a list of instructions (Fig. a), as



functional diagram or contact diagram, direct into the machine code of the control units. They can alsotranslate from the machine code back into the higher-level representation.

Figure (a) Programming languages (Siemens)

A control task can be expressed in different ‘languages’; the list of instructions (a) can also betranslated by simple programming units into a machine language understood by the control system.The functional diagram (b) which is easier to understand by engineers and the ladder diagram (c)which is very popular in USA, impose more exacting demands on the programming unit.

At all events such units can be employed on-line, i.e. connected direct with the controller. Theprograms to be entered in this case are usually entered direct in the programming language of thecontroller, or for display purposes are read out of a memory. In on-line operation it is also possible toperform test functions, fault location and program correction.

A further important function of the programming unit is the program documentation. Specialdocumentation software converts the programs into a form readily understood by the user (auxiliarytext, I/O description, comments, etc.). A printer connected to the system is able to print out thedocumented programs.

Engineering / B07 - Eng / C06 - Motor Control / Motor Control / 2. PROGRAMMABLE CONTROLLERS (PLC) / 2.6 Criteria governingthe Choice of PLC

2.6 Criteria governing the Choice of PLC

Basically, any PLC can be used for control tasks in the cement industry, provided it satisfies tofollowing requirements.

Engineering / B07 - Eng / C06 - Motor Control / Motor Control / 2. PROGRAMMABLE CONTROLLERS (PLC) / 2.6 Criteria governingthe Choice of PLC / 2.6.1 General

2.6.1 General

♦ The system is well represented and generally known in the country

♦ Spare parts are guaranteed obtainable at least for 10 years

♦ The system must be capable for expansions in order to integrate future adaptations

♦ The dimensions of equipment permit the replacement of existing facilities

Engineering / B07 - Eng / C06 - Motor Control / Motor Control / 2. PROGRAMMABLE CONTROLLERS (PLC) / 2.6 Criteria governingthe Choice of PLC / 2.6.2 Central Unit (CPU)



2.6.2 Central Unit (CPU)

♦ When the system is extended to full capacity, the cycle time should not exceed 150 ms

♦ Adapted memory capacity, so that there is no shortage of storage capacity when the system is fullyexpanded.

♦ On-line programming of modifications while the process is in progress

♦ Reasonable set of instructions containing the following:arithmetic with variable decimal point, PID algorithms and functions specified by the user, modules(e.g. motor module).

♦ Floating point arithmetics

Engineering / B07 - Eng / C06 - Motor Control / Motor Control / 2. PROGRAMMABLE CONTROLLERS (PLC) / 2.6 Criteria governingthe Choice of PLC / 2.6.3 Communication

2.6.3 Communication

♦ Between PLC's with bus

♦ Standardised interface with simple protocol with a main-frame computer (e.g. RS 232, RS 422, RS485)

♦ Standardised interface with subcontrol systems (field bus, profibus, RS 232)

Engineering / B07 - Eng / C06 - Motor Control / Motor Control / 2. PROGRAMMABLE CONTROLLERS (PLC) / 2.6 Criteria governingthe Choice of PLC / 2.6.4 Inputs/Outputs

2.6.4 Inputs/Outputs

♦ Decentralised peripherals connected with the CPU by a serial line (possibly an optical link)

♦ 24 V or 48 V DC single-ended inputs/outputs with common ground

♦ 4-20 mA analogue single-ended inputs/outputs with common ground

♦ Capable of extension up to 2000 inputs and outputs

Engineering / B07 - Eng / C06 - Motor Control / Motor Control / 2. PROGRAMMABLE CONTROLLERS (PLC) / 2.6 Criteria governingthe Choice of PLC / 2.6.5 Programming and Documentation

2.6.5 Programming and Documentation

♦ Off-line programming and documentation with standard PC’s

♦ Remote line connection of programming units

♦ Graphic representation, preferably by functional diagram

♦ Symbolic programming of addresses with at least 15 freely chosen characters

♦ Commands and operating instructions in the local language

Motor control - Logic controllerTask: Sequence start and stop of motors, interlocking of motors, machine protection,alarming



Motor control - integratedTask: Sequence start and stop of motors, interlocking of motors,machine protection,alarming, measuring, analog control, reporting

Motor control - Programmable controller: System configuration

Motor control - Programmable controller: Hardware configuration



Motor Control - Programmable controller: Isolation of signals

Motor Control - Programmable controller: Language, presentation

1. Relay European: AND NOT / OR

2. Relay American (Ladderdiagram): AND NOT / OR



3. Logic card European: AND NOT / OR

4. Programmable logic controller: Boolean language, (or logic, or ladder)A AND NOT B = C A OR B = C

Motor Control - Programmable controller: Language, Example

Example:

A: Operator command: Turn motor left

B: Plant feedback: Limit switch left reached

C: Control system command: Turn motor left



D: Operator information lamp: Device in position left

Program Short

1. Input A

2. AND NOT Input B

3. Equals Output C A AND NOT B = C

4. Input B

5. Equals Output D B = D

Motor Control - Programmable controller: Language, timer

Example Timer:

A: Operator command: Turn motor left

B: Plant feedback: Limit switch left reached

C: Control system command: Turn motor left

Program

1. Timer X = 30 seconds

2. Input A

3. Equals timer X

4. Timer X

5. AND NOT input B

6. Equals output C



Motor control - Programmable controller: Language, structured programming

Understanding Computer Technology

Automation systems - Typical configuration



History of PLC’s

1968: Concept of a Programmable Controller

1969: Hardware based CPU

Logic statements, 1 Kbytes Memory, 128 i/o’s

1973: Source Code Editing

1974: PLC with Multi-Processors

Logic, Counter, Timer, Move Words, Arithmetic’s

12 Kbytes Memory, 1024 i/o’s

1976: Decentralised I/O-Systems

1977: Micro Processor based PLC with Logic Co-Processors

1978: Universal I/O-Structure

1979: Bit Slice Processor Architecture

1980: High efficient decentralised I/O-Structure with

intelligent I/O-Modules and Block Transfer Instructions

1981: Data Highway with Medium Response Time(Token Passing)

1982/83: Micro-programmed, with multi-processor PLC’s of 4th Generation

In BASIC programmable Co-Processors

Integrated Hard disk

1985: Intelligent Programming Units

Optical Links

Use of PC’s for programming and debugging

1986 Graphic/Function Programming

More Mass-Storage

1989: ?



1968 Modular Digital Controller

MODICON

♦ General Motors:

• simple to program, easy to change

• maintenance low → modular system

• safe in industrial environment

• size smaller than relay panels

• data communication to other systems

• cheaper than relais

⇓

Programmable Logic Controller

Evolution of Control Systems

40 years of Relay Systems20 years of Solid State10 years of PLC’s

from island to system

Differences between Relay and PLC Programming



Working Principle of a PLC

Block diagram of programmable controller

Advantages of PLC control against relay



PLC-Progamming Language



Engineering / B07 - Eng / C07 - Technical Information Systems (TIS)

C07 - Technical Information Systems (TIS)



Engineering / B07 - Eng / C07 - Technical Information Systems (TIS) / TECHNICAL INFORMATION SYSTEM (TIS)

TECHNICAL INFORMATION SYSTEM (TIS)Urs A. Herzog / Felix FehrHES 98/6348/E

1. INTRODUCTION

2. PROCESS INFORMATION MANAGEMENT

2.1 Introduction to the Improvement Process

2.2 Importance of information for decision making

2.3 Process Information which is relevant for plant performance improvement

3. TECHNICAL INFORMATION SYSTEMS (TIS)

3.1 Types of Automation- and Information System in a plant, Definitions

3.2 Principle of a Technical Information System (TIS)

3.2.1 General

3.2.2 Tasks (requirements) of a TIS

3.2.3 Structure and Integration of a TIS

3.3 TIS Systems and Suppliers

4. TIS APPLICATIONS AND EXPERIENCES

4.1 TIS System installed and planned in “Holderbank” plants

4.1.1 System installed and running

4.1.2 System planned to be installed (Project approved)

4.2 Some Specific Applications and Experiences, Benefits

4.2.1 Alsen Breitenburg Zement - und Kalkwerke GmbH, Lägerdorf, Germany

4.2.2 Buendner Cement AG, Untervaz, Switzerland

4.2.3 Holnam: Holly Hill, Clarksville, Dundee, Artesia; USA

5. TYPICAL PROJECT SCHEDULE AND SCOPE OF SUPPLY

5.1 Project Schedules (typical)

5.2 Scope of supply (typical)

6. RESULTS AND CONCLUSION

6.1 Results, Benefits

6.2 Conclusion

7. REFERENCES:



Engineering / B07 - Eng / C07 - Technical Information Systems (TIS) / TECHNICAL INFORMATION SYSTEM (TIS) / 1. INTRODUCTION

1. INTRODUCTION

Since a few years the cement industry is under continuous pressure to optimise their production ingeneral. One reason is to lower production cost, another is to minimise the use of energy and fulfil theemission limits of new environmental protection legislation. Also cement market asks for new productsand product properties, therefore production modification and expansion must be realised in short time.

To be able to act and react to this continuous challenge, management and personnel responsable ofplant operation must have access to the relevant information about their production, and productionequipment.

Beside the three classical production resources: manpower, capital, real estate, predictions are thatinformation will soon be the forth.

Therefore Information Management Concepts and tools which support the user to get and analyse thisinformation, are getting more and more important:

This paper gives an overview of modern Process Information Management, of available InformationSystems and some experience of applications of such Information Systems.

Engineering / B07 - Eng / C07 - Technical Information Systems (TIS) / TECHNICAL INFORMATION SYSTEM (TIS) / 2. PROCESSINFORMATION MANAGEMENT

2. PROCESS INFORMATION MANAGEMENT

Engineering / B07 - Eng / C07 - Technical Information Systems (TIS) / TECHNICAL INFORMATION SYSTEM (TIS) / 2. PROCESSINFORMATION MANAGEMENT / 2.1 Introduction to the Improvement Process

2.1 Introduction to the Improvement Process

Market competence and changing regulations forces company and plant management to optimisecontinuously the cement manufacturing process to increase production, improve the equipmentperformance, reduce the use of energy, reduce the amount of necessary man-hours, in summary lowerthe overall production cost of our product the cement.

In general, optimisation and improvement is based on the following facts: (according Jim Harrington).

♦ If you want to improve it, you have to control it !

♦ If you want to control it, you have to understand it !

♦ If you want understand it, you have to measure it !

The three activities: measurement, understanding (to analyse data and to come to a conclusion) andcontrol form together the Improvement Loop. Improvement is only sustainable if this improvementloop is executed continuously.

Corporate programs as BCM or MAC fully relay on this improvement loop (e.g KPI measurement,reporting, action meetings, etc.).

Nowadays (since the invention of modern computers) some of Improvement Loop tasks can beexecuted automatically. The most time consuming and boring task of process data acquisition, rawdata handling and report compiling can be done with a computer system. Plant personnel can be usedfor analysing information and for decision making. – This is a more adequate challenge for a human



being than coping numbers.

Engineering / B07 - Eng / C07 - Technical Information Systems (TIS) / TECHNICAL INFORMATION SYSTEM (TIS) / 2. PROCESSINFORMATION MANAGEMENT / 2.2 Importance of information for decision making

2.2 Importance of information for decision making

The basis for management to make the daily operational and the medium term tactical decision, isinformation. Information coming from the process and process related actions as quality control,dispatch, emission monitoring and others.

If the plant or company management want to act - proactively or reactively - they need information. Themore they fine tune the operation (e.g: BCM) and the more they optimise the risks (e.g: MAC), themore comprehensive, reliable, accurate and direct must the information they base there decisions onbe.

A modified quotation from a Japanese Business Expert (name unknown) says it quite direct:

Information is a key success factor for businesssome Managers know this

others are learningthe rest will be Victims.

Engineering / B07 - Eng / C07 - Technical Information Systems (TIS) / TECHNICAL INFORMATION SYSTEM (TIS) / 2. PROCESSINFORMATION MANAGEMENT / 2.3 Process Information which is relevant for plant performance improvement

2.3 Process Information which is relevant for plant performance improvement

For the daily plant operation, as well as for medium and long term plant performances monitoring andimprovement the different responsibilities in a plant need the following type of information on hourly,day, week, month and year basis.:

Company / PlantManagement

• What is the plant performance this day / week / month /year?

• Where is the biggest improvement potential?

• How are we compared to the others (benchmarking)

Production • What is the production rate, consumption, actual stock ofmaterials?

Process • Does the process / equipment runs optimal? - Why not?

Maintenance • What are the equipment runtimes, machine conditions,failures rates? - Failure reasons?

Quality • What is the quality level of our product? Why is it in / out ofspecification?

Energy • What are the specific energy consumption? - Tendencies?

Environment • What are the emissions? Are we endangered to exceedlimits?

In more general terms, the plant personnel needs a tool which provides:



♦ Relevant Information

• at the Right Time

• at the Right Place

• in the Right Form

• to the Right People

• This simple but important statement (from: Rauli Hantikainen) describes the basic requirementof adequate Information Management.

• A computer systems which can fulfil the above mentioned requirements has to be based on aintegrated Database incorporating data sets from all technical related plant disciplines:

Figure 1:

Such system are called: “Technical Information System”.

Engineering / B07 - Eng / C07 - Technical Information Systems (TIS) / TECHNICAL INFORMATION SYSTEM (TIS) / 3. TECHNICALINFORMATION SYSTEMS (TIS)

3. TECHNICAL INFORMATION SYSTEMS (TIS)

In the past, most of the management's planning and optimisation was based on different data printouts,recorder charts and manually generated reports. But nowadays tools and system concept are availableto get immediate and accurate information on there desk top in seconds.

Engineering / B07 - Eng / C07 - Technical Information Systems (TIS) / TECHNICAL INFORMATION SYSTEM (TIS) / 3. TECHNICALINFORMATION SYSTEMS (TIS) / 3.1 Types of Automation- and Information System in a plant, Definitions

3.1 Types of Automation- and Information System in a plant, Definitions

In this paper common industry term as CIM- and ERP- System are used. They are indispensable fordescribing and defining the architectures and system concepts that are involved in plant wideInformation Management system solutions. Their definition is found just below:

♦ CIM = Computer-Integrated Manufacturing systems:

♦ A series of computer-based systems, both business and technical, integrated into a singleconceptual solution. A CIM system is comprised of components and elements of both ERP and TISsystems (see next), as well as the different automation systems like process control, high levelcontrol, quality control (lab), etc.

♦ ERP = Enterprise Resource Planning system:



♦ A integrated, networked computer system providing (primarily) business functions and somemanufacturing functions. An ERP system mostly provides also the information link between thecompany headquarters (HQ) and the plant. In most “Holderbank” Group Companies the productSAP R/3 is implemented (or planned) as a ERP system.

♦ TIS = Technical Information System:

♦ A integrated, networked, real-time computer systems providing (primarily) manufacturing functions.Its real-time data base technology merge all plant automation data with data from the non-technical(or business) systems within a Plant. By capturing “live” information about the manufacturingprocess as, sensor measurement, set-points, run-times, throughput, yields, etc., a TIS canmeasure constraints and identify bottlenecks to better manage and control manufacturingprocesses (see also decryption in chapter 3.2).

♦

(In some industries the term MES, Manufacturing Execution System, is uses also).

The sketch below shows the structure and interactions of the different mentioned systems.

Figure 2:

Engineering / B07 - Eng / C07 - Technical Information Systems (TIS) / TECHNICAL INFORMATION SYSTEM (TIS) / 3. TECHNICALINFORMATION SYSTEMS (TIS) / 3.2 Principle of a Technical Information System (TIS)

3.2 Principle of a Technical Information System (TIS)

Engineering / B07 - Eng / C07 - Technical Information Systems (TIS) / TECHNICAL INFORMATION SYSTEM (TIS) / 3. TECHNICALINFORMATION SYSTEMS (TIS) / 3.2 Principle of a Technical Information System (TIS) / 3.2.1 General

3.2.1 General

In the CIM pyramid, a TIS is locate between the Company / Works Management Level (ERP) andProduction / Process Control Level (Plant Automation). The interaction between those levels is asfollows:

♦ The tactical and strategic decision are made in the higher levels:

• The computer systems on these levels must provide to management business data andcompiled and summarised plant information (process, production, equipment and quality) (timerange: days, month, years).

♦ Operation of the plant is done from the lower level systems.

• The computer systems on these levels must provide to plant responables immediate accurate



real-time process and process related information. (time range: seconds to hours).

♦ A TIS System does the automatic data acquisition and data pre-processing. It provides tools fordata evaluation, create reports, graphs and tables, for status and performance analysis. It alsoserves as a data interface between Operation and Managing Level of a plant and company.

Engineering / B07 - Eng / C07 - Technical Information Systems (TIS) / TECHNICAL INFORMATION SYSTEM (TIS) / 3. TECHNICALINFORMATION SYSTEMS (TIS) / 3.2 Principle of a Technical Information System (TIS) / 3.2.2 Tasks (requirements) of a TIS

3.2.2 Tasks (requirements) of a TIS

Data Acquisition

Data from the process and process related tasks, e.g as material handling, product shipment andquality determination is the basis for compiling the above mentioned information. In a up-to-datecement plant most of this data are already automatically measured by a computer based ProcessControl System (PCS) and other Automation systems (High Level Control, Lab, Dispatch, Emission,etc.). In a standard set-up of a 3000 to 5000 tones per day plant, the PCS measures and handlesroughly 600 analog sensor, 600 counters and integrators and up to 15’000 alarm and event messages.Data acquisition, data processing and visualisation is done in real time (milliseconds to seconds).Historical data is normally presented to the operator in graphic trend charts and data historian is storedfor playback for up to a week, sometime month. The PCS capability is very limited for tasks, as longterm data storage and retrieval, history archiving, data consolidation and report generation.Furthermore data from the lab analyser and dispatch system are normally not interfaced to the PCS.Data acquisition scan time from data of all above mentioned automation system is between 10 to 60seconds.

Data Pre-Processing, Storage and Archiving

All the automatic read in data, is filtered and pre-processed according data type (e.g. integration of akW signal to kWh, conversion of silo distance measurements to silo level, combination of a cementtype signal and a material flow signal to a amount of finish good produced, calculation of specific fuelconsumption out of heat content, flow of fuel, kiln feed and clinker factor etc.).

The different type of scanned and calculated values are then stored in integrated, real-time Database.The data storage structure is optimised for a huge amount of data to be read and retrieved in veryshort time. Archiving and retrieving to and from a tape or disk unit must be possible under on-lineconditions. Raw data lifetime on harddisk is normally 6 to 12 month, on tape between 1 to 10 years (insome special cases as emission data for the EPA, archive data lifetime, must be guaranteed for up to30 years).

Especially a fast and user-friendly data retrieving engine is important. Otherwise the data is buried in aData Graveyard with no use at all. A short estimate of the total amount of data on such a systememphasise the importance of this statement:

♦ Scan time = 1 minute, analog measurements = 1200 tags, amount of alarm and event messages(132 char.) per minute = 1 data lifetime (on disk) = 1 year.

♦ (4 Bytes per number, 1 Byte per character, 4 Bytes per message)

♦ per minute: ==> (1200 * 4) + (132 * 1) + 4 = 5000 Bytes

♦ per day: ==> 60 * 24 * 5000 = 7.2 Mbytes

♦ per year: ==> 365 * 7.2 MB = 2.6 GB (Data Storage Capacity)

Data Evaluation



To analyse this big amount of data it is indispensable to applies specific methods and tools to transferthe raw data to useful information (remember the difficulties to analyse the pyro-process with data onmultiple, endless paper charts strips with no physical scale, date, and remarks on it).

A state-of-the-art TIS provides most of the following Data Analysis and Reporting tools:

♦ Plant Overview Display

• Gives plant management an immediate overview over actual plant- and equipment- operation.

♦ Daily / week / month / year Manufacturing Report

• Summary Report with information about the process, production, equipment status, materialstock, quality, shipment etc.. Medium and long-term performance monitoring.

♦ Operation Log Reports:

• Short term production and process performance monitoring

♦ Trend graphs

• Actual - and historical process status and performances

♦ Alarm List and Alarm Statistic

• Shows actual and historical equipment failures and gives maintenance personnel an overviewof equipment problems.

♦ List of running hours, production numbers and process values

• Enables plant personnel to plan production and maintenance schedules; For special situationsalso Ad-Hoc analysis can be done and special Reports (Emissions for EPA, ATR for“Holderbank”, etc.) can be created.

♦ Statistical Analysis as Charts, Correlation, Pareto

• For Quality control, process optimisation and maintenance support.

Manual Data Entry and Data Modification Capability

For the calculation in the pre-processing (see above) the TIS needs manual entered plant constant.Examples of such plant constants are: clinkerfactor, raw material humidity, head content of fuels, etc. ATIS must provide user-friendly functions to enable plant personnel to adjust the constants in a easyway.

Furthermore, a TIS must provide functions to modify and adjust calculated and integrated reportvalues. In contrast to booking numbers in a transaction based ERP business system, every physicalsensor measurement has a measurement error (independent how often the sensor has beencalibrated). Integration of sensor values result in accumulation of the error. For example in a 2 milliontonnes per year cement plant, a 2% error in the produced cement belt weigher system, results in adivergence of 40’000 tonnes of cement. TIS applications showed that automatic generated reportsmust be checked for plausibility and adjusted accordingly before they can be approved for further use(e.g. as input data for a SAP, ERP system).

Interfaces to Automation- and ERP System

As shown in chapter 3.1, a TIS System is located in between the ERP business system of company /works management level and the automation system of the process / production control level. Thismeans a TIS reads his input data from one or multiple automation system as Process Control System,Lab System, Emission Monitoring System etc.. Compiled reports can be sent to the upper level ERPSystem for further treatment. A TIS supplier must provide and support highly reliable interfaces todifferent brand of automation- and ERP systems.



Engineering / B07 - Eng / C07 - Technical Information Systems (TIS) / TECHNICAL INFORMATION SYSTEM (TIS) / 3. TECHNICALINFORMATION SYSTEMS (TIS) / 3.2 Principle of a Technical Information System (TIS) / 3.2.3 Structure and Integration of a TIS

3.2.3 Structure and Integration of a TIS

The general structure of a TIS and the integration in the plant information management concept looksas follows:

Figure 3:

With this approach, the process related data flows in a structured flow from bottom to top. All systemsare networked, manual data entry is minimised, data transfer speed and data quality are maximised.

What to avoid

In some plants (“Holderbank” and Non-”Holderbank”) the automation- and control systems as well asdifferent business computer systems were installed over several years not applying an overall concept.

This “natural grown” computer system agglomeration are typical patchwork solutions with individualcomputer islands (not using standards).

Such systems are highly complex, difficult to document and maintain and result high operation andsupport costs. The flow of data is limited, because too many systems and interfaces are necessary.Often manual data transfer is used (data printout of one computer system, data entry typing in theother computer). Such approaches are not user friendly, show slow data transfer, low quality of dataand redundant data sets and results in user frustration.

Engineering / B07 - Eng / C07 - Technical Information Systems (TIS) / TECHNICAL INFORMATION SYSTEM (TIS) / 3. TECHNICALINFORMATION SYSTEMS (TIS) / 3.3 TIS Systems and Suppliers

3.3 TIS Systems and Suppliers

The results of different Industry Market Scan (1993 - 1997), executed in co-operation with “Holderbank”Group Companies in various countries, are summarised below. The list shows suppliers, productnames and country of origin:

Supplier Product Origin

ABB CIMS Switzerland

Siemens CEMAT-MIS Germany

AspenTech CIM/21, InfoPlus.21 USA

FLS / Fuller Plant Guide USA / Denmark



FLS / Fuller Plant Guide USA / Denmark

OSI PI System USA

Honeywell Uniformance USA

Engineering / B07 - Eng / C07 - Technical Information Systems (TIS) / TECHNICAL INFORMATION SYSTEM (TIS) / 4. TISAPPLICATIONS AND EXPERIENCES

4. TIS APPLICATIONS AND EXPERIENCES

Engineering / B07 - Eng / C07 - Technical Information Systems (TIS) / TECHNICAL INFORMATION SYSTEM (TIS) / 4. TISAPPLICATIONS AND EXPERIENCES / 4.1 TIS System installed and planned in “Holderbank” plants

4.1 TIS System installed and planned in “Holderbank” plants

Engineering / B07 - Eng / C07 - Technical Information Systems (TIS) / TECHNICAL INFORMATION SYSTEM (TIS) / 4. TISAPPLICATIONS AND EXPERIENCES / 4.1 TIS System installed and planned in “Holderbank” plants / 4.1.1 System installed andrunning

4.1.1 System installed and running

Company / Plant Country TIS Supplier / System Installed

AB GmbH / Lägerdorf Germany Siemens / CEMAT-MIS 1994

BCU / Untervaz Switzerland ABB / CIMS 1995

HOLNAM / Holly Hill,Clarksville, Dundee, Artesia

USA AspenTech / CIM21 1995/96

Alpha / Dudfield, Ulco South Africa ABB / CIMS 1997/98

HOLNAM / all 15 plants(cement and slag)

USA AspenTech / InfoPlus21 1997/98

Engineering / B07 - Eng / C07 - Technical Information Systems (TIS) / TECHNICAL INFORMATION SYSTEM (TIS) / 4. TISAPPLICATIONS AND EXPERIENCES / 4.1 TIS System installed and planned in “Holderbank” plants / 4.1.2 System planned to beinstalled (Project approved)

4.1.2 System planned to be installed (Project approved)

Company / Plant Country TIS Supplier / System planned

HCB / Siggenthal Switzerland ABB / CIMS 1998/99

SCL / Chekka Lebanon under Evaluation 1998

QCL / Gladstone Australia under Evaluation 1998/99

Engineering / B07 - Eng / C07 - Technical Information Systems (TIS) / TECHNICAL INFORMATION SYSTEM (TIS) / 4. TISAPPLICATIONS AND EXPERIENCES / 4.2 Some Specific Applications and Experiences, Benefits



4.2 Some Specific Applications and Experiences, Benefits

Engineering / B07 - Eng / C07 - Technical Information Systems (TIS) / TECHNICAL INFORMATION SYSTEM (TIS) / 4. TISAPPLICATIONS AND EXPERIENCES / 4.2 Some Specific Applications and Experiences, Benefits / 4.2.1 Alsen Breitenburg Zement -und Kalkwerke GmbH, Lägerdorf, Germany

4.2.1 Alsen Breitenburg Zement - und Kalkwerke GmbH, Lägerdorf, Germany

(Main use of TIS: Process Analysis, Quality Monitoring, MAC report data)

Cement plant with 2 kilns, with a capacity of approximately 1.6 mio t/y cement.

The company sells more than 34 different types of products and has to keep track of all the sales andquality of the products. Furthermore the new kiln 11 is designed to be feed with numerous alternativeraw materials and fuels.

TIS System implemented: Siemens CEMAT-MIS

♦ Technical Concept

• Siemens CEMAT-MIS Technical Information System installed in 1994

• The system uses a Server based on a PC (Intel Pentium) running Siemens proprietary DBMSand PC Clients running MS Excel for reporting and data analysis.

• Trend display and analysing tool (extended analysis possible on integrated Excel tool)

• Use standard production, operation reports and custom defined daily production report (realisedon Excel).

• Reads process and production data directly from the Process Control System (PCS = SiemensCEMAT Coros LSB / S5). Reads approx. 2000 analog values and process more all alarms andevent messages, scan rate = 1 minute).

• Quality data from the automatic, roboterised lab system (Polysius POLAB) are feed viainterface directly to the CEMAT-MIS (event driven).

• Data from the Emission Monitoring system are send to the CEMAT-MIS via interface.

• The CEMAT-MIS reads dispatch and sales data once per day from the company mainframe viaASCII file transfer.

• All systems are connected via an Ethernet LAN (H1 and TCP/IP protocol).

• Integrates production, operation, quality, emission and consumption monitoring and reporting.

• More to 16 user PC’s.

• Reports on the plant files server (Novell) can be transfered via modem lines at the terminal andgrinding plant locations.

♦ Experiences / Benefits

• The CEMAT-MIS is a very reliable and adequate performing system (more than two years ofexperiences).

• The excellent trending and reporting features provided a tool to analyse and optimise theprocess easy (for example the ball mill charges). Advantage: TIS calculate the specific energyconsumption for each type of cement individually. With this cement type dependent energyconsumption trends can be monitored which is only possible with automatic data acquisitionand pre-processing via PCS and TIS.

• The CEMAT-MIS was directly used for the commissioning of the new kiln 11. The long-termdata storage and trending function provided a excellent tool to speed up commissioning. It evenprevented the plant to pay the cost for a damaged EP Filter, because with the data from the



CEMAT-MIS the engineers were capable to find the root-cause and the exact time when thedamage happened. So repair cost could be turned over to the suppliers insurance.

• Tailor made reports for the MAC Initiative provide automatically, on daily basis the necessaryproduction- and equipment efficiency- numbers. This data were used to calculate the KPI (KeyProcess Indicators) and are the basis for failure analysis. The biggest benefit from the systemis fast and automatic report generation every morning (sustainable). Data accuracy with thissystem is much better than manual data processing and saves up to 3 man-hours per day.

• Complex process analysis realised with correlation charts provide new perceptions, which helpto increase production equipment efficiency.

• System is very well accepted and used by plant personnel.

♦ Further Proceeding and Projects

• In 1998 a SAP R/3 ERP System will replace the now used mainframe system.

• An interface for data exchange between the SAP R/3 and the Siemens CEMAT-MIS systems isforeseen. The planed use of this interface is to transfer form the TIS failure reasons andequipment running hours in the SAP Plant Maintenance Module (PM). A study will check thepossibility to use the SAP Production Planning Module (PP) with production numbers from theTIS.

Engineering / B07 - Eng / C07 - Technical Information Systems (TIS) / TECHNICAL INFORMATION SYSTEM (TIS) / 4. TISAPPLICATIONS AND EXPERIENCES / 4.2 Some Specific Applications and Experiences, Benefits / 4.2.2 Buendner Cement AG,Untervaz, Switzerland

4.2.2 Buendner Cement AG, Untervaz, Switzerland

(Main use of TIS: Emission Reporting, Overall Manufacturing Report, Energy Reporting).

Cement plant with 2 kilns with a capacity of 1 mio t/y cement.

TIS System implemented: ABB CIMS


• ABB CIMS Technical Information System installed in 1994/95.

• Reads process and production data directly from the Process Control System (PCS), realisedwith an Allen Bradley PLC 5 and PC based HMI system (reads approx. 600 analog values andprocess up to 15’000 alarms and event messages, scan rate = 1 minute).

• Integrates production-, operation, consumption and emission monitoring and reporting.

• Trend display and analysing tool (extended analysis possible on integrated EXCEL tool).

• CIMS is a Server / Client solution based on DEC Alpha server running a Oracle DBMS and PCClients running MS Access and Excel for reporting and data analysis.

• Use standard production and operation reports and custom defined emission report (realised onAccess).

• CIMS can consolidate (and compress) data to hour, shift, day, month and year values andstores data for on-line access up to 1 year.


• Improved and faster monitoring and reporting of emission data to EPA.

• Tool to analyse operating and emission data which improved the use of HWDF burning.

• Reduced drastically the man-hours (up to 2 man-hours daily) needed for manual data entry andmanual analysis to generate emission and production reports.



• A sophisticated Overall Manufacturing Report provide on daily and monthly basis a summary ofkey process, production, consumption, efficiencies, stock and quality data. Saves productionmanagement up to 0.5 man-hour daily.


• Expand CIMS for enhanced production reporting and detailed electrical consumption reporting.

• An interface for data exchange between the SAP R/3 and the ABB CIMS systems is foreseen(flow of material, equipment runhours and condition).

• Adapted reports for support for MAC Initiative.

Engineering / B07 - Eng / C07 - Technical Information Systems (TIS) / TECHNICAL INFORMATION SYSTEM (TIS) / 4. TISAPPLICATIONS AND EXPERIENCES / 4.2 Some Specific Applications and Experiences, Benefits / 4.2.3 Holnam: Holly Hill,Clarksville, Dundee, Artesia; USA

4.2.3 Holnam: Holly Hill, Clarksville, Dundee, Artesia; USA

(Main use of TIS: Emission Reporting, Process Analysis).

Four Cement plants which burn HWDF (Hazardous Waste Derived Fuel). Legislation force them tomonitor emission (based on gas analyser and materiel input model calculation).

TIS System implemented: AspenTech CIM21 (former company: ISI)


• AspenTech CIM21 Technical Information System installed in 1995 and 1996

• Reads process and production data directly from the Process Control System (PCS), realisedwith a Modicon PLC and Gensym G2 based HMI systems (reads approx. 200 - 330 analogvalues per kiln, scan rate = 1 minute).

• Integrates emission monitoring and reporting.

• Trend display and analysing tool (extended analysis possible on EXCEL tool).

• CIM21 runs on UNIX based HP workstation server. The Database is proprietary. PC (underX-Window) can be used as user interface.


• Provide the mandatory (according EPA) emission monitoring, reporting and data archiving.

• HWDF burning would not be possible without this TIS systems.

• The system is also used for process data analysis (mainly graphic trend) because trendingfeatures of the used PCS are not sufficient.


• Upgrade the existing CIM21 system with the new InfoPlus21 (NT based Client /Server System).

• Install in the remaining 11 plant a InfoPlus21. Use mainly as process data historian andemission monitoring tool.

• The company wide “Manufacturing Data Integration” (MDI) project will integrate these TIS in theERP Datawarehouse (Holnam proprietary Data Management System based on Oracle).

Engineering / B07 - Eng / C07 - Technical Information Systems (TIS) / TECHNICAL INFORMATION SYSTEM (TIS) / 5. TYPICALPROJECT SCHEDULE AND SCOPE OF SUPPLY

5. TYPICAL PROJECT SCHEDULE AND SCOPE OF SUPPLY



Engineering / B07 - Eng / C07 - Technical Information Systems (TIS) / TECHNICAL INFORMATION SYSTEM (TIS) / 5. TYPICALPROJECT SCHEDULE AND SCOPE OF SUPPLY / 5.1 Project Schedules (typical)

5.1 Project Schedules (typical)

The introduction of a TIS system needs some pre-project investigations resulting in a detailedspecification. With this, an evaluation (bidding process) can be executed to find the most appropriateTIS. Normally a TIS is implemented in steps, similar to a SAP, realising the functions with the highestpriorities first. The following schedule gives some indications of the whole procedure.

Phase Actions

0: Pre-condition The plant must be equipped with a state-of-the-art computerbasedProcess Control System (PCS).

1: Study Investigation study to determine plant requirements, elaboration of aconcept. Investigate integration in plant /company computerinfrastructure. Check of interface solutions to all automation systemsand to the ERP system.

2: Project Planning Creation of a Specification and elaboration of a budget and animplementation schedule.

3: Tendering andEvaluation, Offer

Creation of a tender document. Execution of a system evaluationand selection of a System / Supplier (in some case evaluation canbe skipped if a company standard exist).

Ask for offer (using specification and schedule).

4: Implementation ofStep 1

Implementation and commissioning of TIS basis System. Check ofperformance, adaption of functions to meet plant requirement, (ifnecessary).

5: Implementation ofStep 2

...............................

Engineering / B07 - Eng / C07 - Technical Information Systems (TIS) / TECHNICAL INFORMATION SYSTEM (TIS) / 5. TYPICALPROJECT SCHEDULE AND SCOPE OF SUPPLY / 5.2 Scope of supply (typical)

5.2 Scope of supply (typical)

The scope of supply of a TIS application may vary from plant to plant, as the requirements aredifferent.

Nevertheless there are basic requirements in a typical cement plant that can be satisfied (usually in afirst implementation phase). That is why the scope of supply is roughly divided into Basic System andOptions. The experience shows, that a cost estimation cannot be given at this place, becausefunctionality, interfaces and numbers of users differ from project to project. But it is important to know,



that project costs are higher than system costs, because time and cost intensive tasks (study,specification, evaluation, see schedule in 5.1) must be done prior to the system implementation.

The following sketch gives an overview of different packages of a TIS basis system (1...4) with options(5...7).

Figure 4:

TIS Basis System (for reference see number in sketch)

1) Server Hardware (HW) an Software (SW), TIS basis SW including DataBase

2) 4 User PC SW license for basis data evaluation

3) Interface driver SW for data acquisition from a Process Control System (PCS)

4) Application applying standard reports and evaluation methods, including systeminstallation and user training

TIS System Options (for reference see number in sketch)

5) Extended functionality as Maintenance Support Functions, SPC, plant specificManufacturing Reports, etc.

6) Interface to Lab or Dispatch (weighing) system

7) Interface to SAP System, including data exchange concept

a) Hardware is part of the plant computer infrastructure

b) not included is set-up and configuration on interfaced system

Assistance from HMC/HES

HMC offers its assistance and experience for TIS Implementation in a plant or group:

♦ audit

♦ elaboration of (detailed) specifications and tender documents

♦ evaluation of offers from different suppliers



♦ general project assistance

♦ detailed engineering of reports (optional)

♦ training for plant personel (optional)

♦ performing aceptance tests

Engineering / B07 - Eng / C07 - Technical Information Systems (TIS) / TECHNICAL INFORMATION SYSTEM (TIS) / 6. RESULTS ANDCONCLUSION

6. RESULTS AND CONCLUSION

Engineering / B07 - Eng / C07 - Technical Information Systems (TIS) / TECHNICAL INFORMATION SYSTEM (TIS) / 6. RESULTS ANDCONCLUSION / 6.1 Results, Benefits

6.1 Results, Benefits

The Experience and results from different Process Information Management Projects in the cementand other basic industries show the following benefits:

♦ Fast and accurate information

• Fast and accurate information enables the plant management to see tendencies and to reactand direct measures before limits were exceeded. Because reports were calculatedautomatically, response time is hours or days, not month.

♦ Open information exchange

• All managers which use any kind of integrated Information Management System (not necessarya TIS) confirm that such tools enables open information exchange which improves teamworkdrastically and minimises mistrust. This because every user has access to the sameinformation. People share information and work closer together.∗ In projects were an interface between the ERP System (e.g. SAP R/3) and the TIS are

planned, personnel responsible for the process and administrative personnel form aninterdisciplinary team, were both sides start to understand also the problems and therequirements of “the other side”.

♦ Indispensable for sustainable optimisation

• High sophisticated Optimising System as LINKman High Level Control need to be fine tunedand adapted to changing process conditions. Only continuous monitoring of the performanceand process conditions with specific analysis tools, as Correlation's, prevent from decreasingsystem performance.∗ In one plant the LINKman runtime can be maintained continuously over 95% with the help of

daily performance feedback, which allows immediate reaction to arising problems.∗ Permanent monitoring of key parameters and adapted analysis methods like Statistical

Process Control (SPC) provides vital information about equipment status and equipmentfailures. Maintenance Improvement procedures (like the one in MAC) relay on such type offeedback data.

♦ Fulfil legislation requirements

• Legislation forces us to monitor, analyse and report certain critical values. (e.g emission, use ofwaste fuel). In USA (BIF) and Switzerland (TA Luft) monitoring, reporting and data archiving ofemissions and waste fuel with a TIS, were accept by the local EPA‘s.

• Continuous Quality monitoring of shipped cement (e.g.: Germany: Cement Norm VDZ, USA:



Mill Certificate) can be realised with the help of a TIS.

♦ Saves man-hour

• In all plant using a TIS, plant management claim man-hour savings. But the even biggeradvantage is, that a TIS frees the engineers from formal work (like data entry, manual dataprocessing) and allows him to use more time on the data analysis.

• Studies of TIS applications in different basic industries show:∗ Reduced data entry time: 75% ∗ (reports are compiled in 3 minutes, and checked in 5 minutes)∗ Reduced Paperwork: up 50%

Engineering / B07 - Eng / C07 - Technical Information Systems (TIS) / TECHNICAL INFORMATION SYSTEM (TIS) / 6. RESULTS ANDCONCLUSION / 6.2 Conclusion

6.2 Conclusion

Considering the importance of relevant information, the actual trends in Information Technology, theindications we have from Technology Watches of non-cement and cement industries (our competitors)and the experiences from TIS and SAP applications result in the following conclusions:

♦ A competitive optimised plant has to be based on computerbased, integrated InformationManagement System (according CIM concept).

♦ Process Information Management with a TIS is a central pillar of such an “Integrated Plant”.Individual users are empowered at the desktop. Process Data feedback and intelligent use of thisinformation is indispensable for a continuous improvement process and will help the plant to becompetitive.

Engineering / B07 - Eng / C07 - Technical Information Systems (TIS) / TECHNICAL INFORMATION SYSTEM (TIS) / 7. REFERENCES:

7. REFERENCES:

♦ U. Herzog, T. Carpenter: Manufacturing Data Integration: Holnam MDI Feasibility Study, IndustrialScan, 1996, HES Report 96/6340/E

♦ U. Herzog: Technical Information System, “Holderbank” E-Circle NA, Mobile (AL), USA, 1996

♦ W. Sedlmeir: Total Management Information, World Cement Feb. 1996

♦ L. Krings: New Cement Information Management Solutions, IEEE Conference 1996, Los Angeles,USA

♦ R. Säuberli: Process and Quality Control Automation, Information Management; “Holderbank” 33rdTechnical Meeting 1994 Basel, Switzerland

♦ R. Säuberli, U. Herzog, H. Rosemann: Process Control and Information Management; VDZKongress 1993 Düsseldorf Germany, ZKG 46 (1993), No 11

Special Thank also to:

♦ Peter Kuenne, Fritz Schneider, Ian Campbell; for discussing and providing information aboutconcept and experiences of the MAC Initiative.

♦ Ivo Keller, Urs Bleisch, Michel Moser, Thorsten Fuchs; for discussing and providing informationabout SAP projects concept, plans and experiences.



Engineering / B07 - Eng / C08 - Case Studies

C08 - Case Studies



Engineering / B07 - Eng / C08 - Case Studies / Engineering - Case Studies

Engineering - Case Studies

Case studies are not included here.



Engineering / B07 - Eng / C09 - Project Engineering

C09 - Project Engineering



Engineering / B07 - Eng / C09 - Project Engineering / Introduction to "Holderbank" Corporate Engineering (CE)

Introduction to "Holderbank" Corporate Engineering (CE)

This presentation is not included here.

Handouts will be provided during the presentations by CE.



Engineering / B07 - Eng / C10 - Introduction

C10 - Introduction



Engineering / B07 - Eng / C10 - Introduction / Procedures to Effective and Efficient Capital Expenditures

Procedures to Effective and Efficient Capital Expenditures

Below is a brief summary and the table of contents of the 'CAPEX Guide'.A full copy will be handed out during the presentation by CE.

Guide to Effective and EfficientCapital Expenditures

(CAPEX)

Summary:

The document at hand is a policy paper for "Holderbank" Group companies, structuring the basis andthe approach for preparing and executing capital expenditure (CAPEX) projects based on the mindsetof Better Cost Management (BCM). In order to give practical support to all those involved in CAPEXprojects, this Capital Expenditure Guide describes the means for proper identification of such projects,provides a generic project structure and content of the project phases and highlights the importance ofand the method for financial evaluation of CAPEX.

TABLE OF CONTENTS

INTRODUCTION

OBJECTIVES OF THE GUIDE

IDENTIFICATION OF POTENTIAL PROJECTS

Company Strategy and Business Plan

Plant Master Plan

PHASES OF PROJECTS



Phase 1: Studies

Phase 2: Basic Engineering

Phase 3: Detailed Engineering/Project Execution/Construction/

Phase 4: Start-up and Commissioning

Phase 5: Post Investment Audit

CLASSIFICATION AND FINANCIAL EVALUATION ASPECTS OF CAPEX

"Holderbank" Classification of CAPEX Types

Replacement investments

Rationalization investments

Expansion and diversification investments

Improvement of product quality investments

Social and safety investments

Environment investments

Financial Evaluation of CAPEX

ANNEXES:

Annex 1: Standard Procedures and Guides Annex 2: Business Planning Cycle: From Strategic Assessment to Yearly Actions & Budgets Annex 3: CAPEX Project Implementation: Phases and Interactions Annex 4: Accuracy of Investment Cost EstimatesAnnex 5: Glossary (selected terms only)



Engineering / B07 - Eng / C10 - Introduction / Brief Guide and Checklist for Capital Expenditure Projects for Replacement andModifications of existing Plant Facilities

Brief Guide and Checklist for Capital Expenditure Projects for Replacementand Modifications of existing Plant Facilities

1. GENERAL

1.1 Definition of Project

1.2 Initiation of Project

2. STUDIES

3. BASIC ENGINEERING

4. DETAILED ENGINEERING / PROJECT EXECUTION

PROJECT MANAGEMENT

Key Issues

Engineering / B07 - Eng / C10 - Introduction / Brief Guide and Checklist for Capital Expenditure Projects for Replacement andModifications of existing Plant Facilities / 1. GENERAL

1. GENERAL

Engineering / B07 - Eng / C10 - Introduction / Brief Guide and Checklist for Capital Expenditure Projects for Replacement andModifications of existing Plant Facilities / 1. GENERAL / 1.1 Definition of Project

1.1 Definition of Project

♦ Technical idea / concept to be studied and or realized.

Main features:

♦ Project has to fulfill certain requirements, assure certain performances.

♦ Project has defined start and end, time required depends on internal and external constraints

♦ Project has a limited budget

♦ Project requires special organization, it is often disturbing factor in permanent organization

Engineering / B07 - Eng / C10 - Introduction / Brief Guide and Checklist for Capital Expenditure Projects for Replacement andModifications of existing Plant Facilities / 1. GENERAL / 1.2 Initiation of Project

1.2 Initiation of Project

♦ Initiated project should be outflow from masterplan



♦ Initiation shall be done in written form:

• setting of objectives

• establish main tasks and responsibilities

• name project manager and project team

• outline stepwise procedure

Engineering / B07 - Eng / C10 - Introduction / Brief Guide and Checklist for Capital Expenditure Projects for Replacement andModifications of existing Plant Facilities / 2. STUDIES

2. STUDIES

♦ Set-up organization and procedures

♦ Review of requirements compared with present situation (same / higher / lower), all partiesconcerned to be involved

♦ Study of alternative solutions, at later stage time will not be available (literature, suppliers, HMC)

♦ Assessment of alternatives based on:

• technical criteria

• experience / references

• economical aspects

♦ Decision to proceed with project

-> introduction in investment list or presentation of investment proposal (possibly in BasicEngineering Phase)

Engineering / B07 - Eng / C10 - Introduction / Brief Guide and Checklist for Capital Expenditure Projects for Replacement andModifications of existing Plant Facilities / 3. BASIC ENGINEERING

3. BASIC ENGINEERING

♦ Adapt organization and procedures to project phase

♦ Establish contracting plan

• Taking into account complexity of project, own resources etc.

• choice between:∗ detail engineering (several contracts)∗ packages (2 to 3 contracts)∗ turn-key (1 contract)

Detail engineering is being preferred solution for "Holderbank".

• Establish time schedule with key events

• Preparation of Tender Document

Note: - Tender Document shall only be issued once high probability of projectrealization is being established.

Purpose: - Definition of technical criteria, scope of supply and commercial conditions

- Safeguard interest of Client



- Provide basis to Tenderers to prepare Tender

- Provide basis to Client to evaluate Tenders

Form: - Tender Document preferably issued in future Contract Form

♦ Preselection of Tenderers

• at least 3 to 4 Tenderers

♦ Evaluation of Tenders

Comparison tables to be prepared containing:

• technical data

• scope of supply

• warranties

• experience / references

• commercial conditions

The evaluation criteria are laid down in the Tender Document.

Tables can be prepared during Tendering Period, do not await Evaluation Period.

♦ Preparation of investment request => Approval by Management to proceed with realization ofproject

Engineering / B07 - Eng / C10 - Introduction / Brief Guide and Checklist for Capital Expenditure Projects for Replacement andModifications of existing Plant Facilities / 4. DETAILED ENGINEERING / PROJECT EXECUTION

4. DETAILED ENGINEERING / PROJECT EXECUTION

♦ Adjust project organization and procedures to requirements

♦ Contract negotiations

• at least 2 potential Contractors to create competitive situation

• technical aspects and warranties to be clarified first

• price negotiations to be assured by small team and not carried out under time pressure, applytarget price policy.

• all contractual matters to be solved during negotiations and incorporated into Contract, inexecution phase power of Client is being reduced.

♦ Establish tight cost and time control

♦ Check and approval of Contractor's drawings, to be done with necessary care, concerned parties tobe engaged (production, maintenance)

♦ Workshop inspection

• engagement of outside experts to be considered (global purchasing of Contractors)

♦ Site supervision

• adequate site supervision to be assured, also required to coordinate site activities with plantoperations

• establish and update list of deficiencies

♦ Start-up and Commissioning



• involvement of personnel from operations and maintenance

• arrange foreseen performance tests

♦ Project audit

• to be carried out about 12 months after commissioning by project team and operations /maintenance

• review of following:∗ project execution∗ performance, recalculate savings, IRR and pay-back period and compare with investment

request∗ outline of conclusions for present and future projects

Annex 1: Investment Cost Estimate

Annex 2: Investment Proposal / Request

Annex 3: Tender Document / Table of Content

Annex 1INVESTMENT COST ESTIMATE (for small projects)

Project : ................................................................

Phase : .................................................................Description Cost

USDCostUSD

1. Dismantling and Demolishing Dismantling M&E-Equipment .......... Dismantling steel structure .......... Demolishing civil structures .......... Disposal equipment, steel and civil structures ..........Total 1 : Dismantling and Demolishing - ..........2. Mechanical Equipment: Group No. 1: .............................. Machine No. 1 : ................................. .......... Machine No. 2 : ................................. .......... Machine No. 3 : ................................. .......... Machine No. 4 : ................................. .......... Total Group No. 1 - .......... Group No. 2: .............................. Machine No. 1 : ................................. .......... Machine No. 2 : ................................. .......... Machine No. 3 : ................................. .......... Machine No. 4 : .............................. ..........



Description CostUSD

CostUSD

Total Group No. 2 - .......... Total Mechanical Equipment (Basis FCA) - .......... Transport and Insurance .......... Taxes and Duties .......... Temporary Installations .......... Erection .......... Commissioning ..........Total 2 : Mechanical Equipment - ..........3. Electrical Equipment Medium Voltage Distribution & Transformers .......... Low Voltage Distribution and Motor Control Centers .......... Plant Automation .......... Instrumentation .......... Drives and Motors .......... Cabling, Grounding, Lightning Protection .......... Total Electrical Equipment (Basis FCA) - .......... Transport and Insurance .......... Taxes and Duties .......... Installations .......... Commissioning ..........Total 3 : Electrical Equipment - ..........



4. Structural Steel and Civil Works Preparatory Work: Soil investigations .......... Site preparation .......... Temporary structures and works .......... Total Preparatory Work - .......... Structure 1 :........................................ .......... Excavation .......... Concrete Works .......... Structural Steel Works .......... Various (blockworks, doors, windows, etc.) .......... Total Structure 1 - .......... Structure 2 ........................................ .......... Excavation .......... Concrete Works .......... Structural Steel Works .......... Various (blockworks, door, windows, etc.) .......... Total Structure 2 - .......... Infrastructure : .......... Roads and squares .......... Ducts and trenches for utilities .......... Various .......... Total Infrastructure - ..........Total 4 : Structural Steel and Civil Works - ..........5. Engineering Mechanical Engineering .......... Electrical Engineering .......... Civil Engineering .......... Fees for Permits, All Risk Insurance, etc. ..........Total 5 : Engineering - ..........6. Various Contingencies ..........Total 6 : Various - ..........

GRAND TOTAL 1-6 - ..........

Above cost estimate does not include VAT and cost for spare parts.

Date: .............................. Name and Signature: .........................................



Investment Cost Estimate

Typical Cost Structure in %

1. Mechanical Equipment 100 %

1.1 Transport and Insurance 5 % of 1.

1.2 Erection and Commissioning 30 % of 1.

2. Electrical Equipment 30 % of 1.

2.1 Transport and Insurance 5 % of 2.

2.2 Erection and Commissioning 30 - 50 % of 2.

Accuracy of Investment Cost Estimate

Phase: Studies + 20 %

Basic Engineering + 10 %

Detailed Engineering + 5 %

Annex 2

INVESTMENT PROPOSAL / REQUEST

Project : ...........................................

1) PRESENT SITUATION

• Description of problems

• Loss of production

• Extra cost involved (production, maintenance)

2) ALTERNATIVES INVESTIGATED

• Description of alternatives

• Advantages / Disadvantages

• Selection of alternative(s)

3) SOLUTION PROPOSED

• Detailed description

• Proposed suppliers

• References



4) INVESTMENT COST ESTIMATE

• Basis of cost estimate

• Cost estimate (budget)

5) ECONOMICAL EVALUATION

• Cost difference (savings) between present situation and proposed solution

• IRR-Calculation

• Pay-back-calculation (usually not more than 2 to 3 years)

6) TIME SCHEDULE

• Duration of project execution

• Critical path

Annexes : Investment cost estimate

Date: ......................

Name and Signature: ................................................................................

Approved:

Date: ......................

Name and Signature: ................................................................................

Comments:

Annex 3



TENDER DOCUMENT

TABLE OF CONTENT

PART A : Tendering Conditions

♦ General Information

• Purpose

• Client

• Brief description of project

• Scope of tender

• Proposed time schedule

♦ Conditions of Tendering

• Commercial part∗ Lumpsum price in ... currency∗ Price breakdown and weights∗ Time schedule∗ Comments on supply contract proposal

• Technical part∗ Technical specifications∗ Technical specification sheets∗ Schematas and drawings∗ Reference list∗ Warranties∗ Alternative proposals

• Date of submission of tenders

PART B : Contract Proposal

♦ Supply Contract Proposal

♦ Annex 1 : General Information

• Information on existing equipment related to project

• Process data to be observed for proposed project

• Material data (raw materials, additives, correctives, cement compositions, etc.)

♦ Annex 2 : General Requirements on Mechanical Equipment

• Standards to be applied

• Standardization (gears, clutches, etc.)



• Requirements and design criteria on individual equipment (e.g. filters, conveyors)

• Painting and colour codes

♦ Annex 3 : General Requirements on Electrical Equipment

• Standards to be applied

• Voltage levels

• Standardization (instruments, safety devices etc.)

• Sub-control systems

• Drives

♦ Annex 4 : Technical Specifications

• Supplier's specifications (from successful Tenderer)

• Technical specification sheets

♦ Annex 5 : Services

• Mechanical Engineering

• Electrical Engineering

• Civil Engineering

♦ Annex 6 : Time Schedule

• Detailed time schedule

♦ Annex 7 : Price Breakdown

• Individual prices and weights (from successful Tenderer)

♦ Annex 8 : Performance Warranties and Tests

• Procedures for measurements of warranties and conducting of performance tests

♦ Annex 9 : Workshop Inspections

• Tests to be conducted by contractor at individual manufacturing steps

• Tests to be carried out by Client / Engineer at individual manufacturing steps

♦ Annex 10 : Drawings

• Flowsheet

• Arrangement drawings

SUPPLY CONTRACT



Key Conditions

1. PRICE

• Fixed lumpsum price, preferably in local currency

2. PAYMENT CONDITIONS

• 20 (30) % as down payment, against advance payment bond for amounts above USD 50'000.--

• 50 (60) % at delivery

• 10 (20) % at provisional acceptance against warranty bond

3. TIME SCHEDULE

• Overall time schedule

• Special schedule (shut down period, etc.)

4. WARRANTY PERIOD

• 12 (24) months starting from provisional acceptance

5. WARRANTIES

• Delivery time

• Overall time for project execution (from coming into force up to provisional acceptance)

• Shut-down time

• Performance (capacities, clean gas content of filters)

• Function and quantity

• Lifetime of special parts (e.g. gear boxes up to 5 years)

• Lifetime of wear parts (e.g. filter bags up to 2 years)

6. PENALTIES

• Penalties due in case of non fulfillment of above warranties except for clean gas content, whichhas to be achieved.∗ Penalties in % of lumpsum price for delays and non fulfillment of performances∗ Replacement (partial) of equipment not reaching lifetime

7. INSURANCE

• Transport insurance by Contractor

• Third party liability insurance by Contractor

• Erection Insurance / All Risk Insurance by Contractor or Client

8. BONDS

• Bonds to be issued by a first class bank, occasionally Concern Guarantees are being accepted.



9. MODIFICATION OF CONTRACT

• Modification to be agreed in writing

10. COMING INTO FORCE

• Conditions to be clearly defined.

Organization Chart



Engineering / B07 - Eng / C11 - General Project Procedure

C11 - General Project Procedure



Engineering / B07 - Eng / C11 - General Project Procedure / The Strip-down Concept for Plant Engineering

The Strip-down Concept for Plant Engineering

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Engineering / B07 - Eng / C12 - Project Identification and Technical Concept

C12 - Project Identification and Technical Concept



Engineering / B07 - Eng / C12 - Project Identification and Technical Concept / PLANT MASTER PLAN

PLANT MASTER PLAN

1. INTRODUCTION

2. CLARIFICATION OF TERMINOLOGY

3. PLANT MASTER PLANS: COMMON PROBLEMS

4. INTEGRATION IN COMPANY’S PLANNING CYCLE

5. CONTENT AND STRUCTURE OF PLANT MASTER PLAN

PROCEDURE FOR ELABORATON OF PLANT MASTER PLANS

7. CONCLUSION AND KEY MESSAGES



Engineering / B07 - Eng / C12 - Project Identification and Technical Concept / PLANT MASTER PLAN / 1. INTRODUCTION

1. INTRODUCTION

In periods of growing demand, investors usually take the opportunity to set milestones in direction ofimproving productivity and expanding capacity as well as controlling cost. New plants, or suitable plantextensions, are the appropriate answers then. In period of harsh competition, shrinking market shares,high interest rates and thus tight investment budgets, it proves to be difficult to even keep up the paceof change in technology.

Comprehensive know-how and adequate assistance are always required to adapt the company to thechanging requirements and the future needs.

As the immediate and future needs of a company are determined mainly through a dynamic process ofchanging parameters of the environment, a dynamic planning instrument must be used for theidentification and registration of these needs.

This appropriate instrument is called Plant Master Plan.

Engineering / B07 - Eng / C12 - Project Identification and Technical Concept / PLANT MASTER PLAN / 2. CLARIFICATION OFTERMINOLOGY

2. CLARIFICATION OF TERMINOLOGY

Plant Master Plans are, since a long time, a well known planning tool on plant level. However, so far,there was no common understanding on purpose and content of Plant Master Plans and for this reasona vast variety of plans were called Plant Master Plans.

In recent years attempts were made in the “Holderbank” Group to standardize the Company PlanningCycle and in particular the Business Planning Process. This standardization called for a clear definitionof the objectives and the contents of Plant Master Plans: The Plant Master Plan shall be the tool forplant management, comprehensively outlining the operational measures and CAPEX projects to beimplemented in the plan period.

“The Plant Master Plan” is a strategic paper outlining the development of the plant in all its fields ofactivity, taking into account the directives of the corporate strategy and the relevant external andinternal factors.

Engineering / B07 - Eng / C12 - Project Identification and Technical Concept / PLANT MASTER PLAN / 3. PLANT MASTER PLANS:COMMON PROBLEMS



3. PLANT MASTER PLANS: COMMON PROBLEMS

A closer look at the realities of Plant Master Planning reveals following common problems:

Analysis of these problems shows that they touch 1) the integration of the Plant Master Plan into thecompany’s planning cycle, 2) the content and structure of the Plant Master Plans, and 3) the procedurefor elaborating Plant Master Plans.

Properly addressing these three problems provides in fact the keys to successful Plant MasterPlanning. If these three elements are mastered, the result then is a Plant Master Plan which is a helpfuland valid tool for plant management to operate and develop their plant in compliance with companystrategy and Business Plan objectives.

Engineering / B07 - Eng / C12 - Project Identification and Technical Concept / PLANT MASTER PLAN / 4. INTEGRATION INCOMPANY’S PLANNING CYCLE

4. INTEGRATION IN COMPANY’S PLANNING CYCLE

Elaborating a Business Plan and the corresponding Plant Master Plan(s) is an iterative process: On theone hand, the Plant Master Plan translates strategy into operational measures and on the other hand itprovides input to the Business Plan, e.g. production and investment costs.



Engineering / B07 - Eng / C12 - Project Identification and Technical Concept / PLANT MASTER PLAN / 5. CONTENT ANDSTRUCTURE OF PLANT MASTER PLAN

5. CONTENT AND STRUCTURE OF PLANT MASTER PLAN

The Plant Master Plan identifies gaps in the areas of materials and energy supply (from main rawmaterials and fuels to alternative raw materials and fuels and mineral components etc.), productionprocess and plant (from raw material extraction to dispatch, internal and external infrastructure etc.)and plant organization and supporting functions (from organizational structure to crossfunctionalprocesses, like maintenance, quality assurance etc.).

The Plant Master Plan clearly defines operational measures and CAPEX projects and indicatespriorities, cost impacts and financial benefits.

Engineering / B07 - Eng / C12 - Project Identification and Technical Concept / PLANT MASTER PLAN / 6. PROCEDURE FORELABORATON OF PLANT MASTER PLANS

6. PROCEDURE FOR ELABORATON OF PLANT MASTER PLANS



To assure comprehensiveness of the Plant Master Plan, the team put together to elaborate such aPlant Master Plan must be composed interdisciplinarily, providing knowledge and experience from allrelevant areas and disciplines.

On the other hand such a team should include not only plant staff but also representatives of thecompany management to assure that those who will be responsible for its implementation are reallycommitted to the proposals and priorities of the resulting Plant Master Plan.

Including external experts, from HMC and/or from other companies and their plant, further helps tochallenge the status quo and to consider a variety of alternatives (Faster Learning Organization).Priority focus must be on optimum exploitation of existing installations in order to minimize CAPEX.

Engineering / B07 - Eng / C12 - Project Identification and Technical Concept / PLANT MASTER PLAN / 7. CONCLUSION AND KEYMESSAGES

7. CONCLUSION AND KEY MESSAGES



Engineering / B07 - Eng / C13 - Massflow

C13 - Massflow



Engineering / B07 - Eng / C13 - Massflow / Project Risk Management

Project Risk Management

1. SLIDE 1: CEMENT COURSE 2000

2. SLIDE 2: PROJECT RISK MANAGEMENT

3. SLIDE 3: BUSINESS RISK MANAGEMENT



6. SLIDE 6: HOLDERBANK GENERIC RISK MAP

7. SLIDE 7: CASE

8. SLIDE 8: CASE

9. SLIDE 9: RISK MODEL FOR CAPEX PROJECTS

10. SLIDE 10: RISK MODELS – DEFINITIONS OF RISKS

11. SLIDE 11: RISK MODELS – DEFINITION OF RISK

12. SLIDE 12: PROJECT CATEGORIES AND RISK MODELS


14. SLIDE 14: WHY RISK MANAGEMENT IN PROJECTS





19. SLIDE 19: BRMP FOR SMALL PROJECTS




23. SLIDE 23: BRMP FOR MEDIUM AND BIG PROJECTS

24. SLIDE 24: MEDIUM AND BIG PROJECTS

25. SLIDE 25: PROJECT RISK MAP

26. SLIDE 26: RISK DRIVER MIND-MAP

Engineering / B07 - Eng / C13 - Massflow / Project Risk Management / 1. SLIDE 1: CEMENT COURSE 2000



1. SLIDE 1: CEMENT COURSE 2000

Engineering / B07 - Eng / C13 - Massflow / Project Risk Management / 2. SLIDE 2: PROJECT RISK MANAGEMENT

2. SLIDE 2: PROJECT RISK MANAGEMENT

Engineering / B07 - Eng / C13 - Massflow / Project Risk Management / 3. SLIDE 3: BUSINESS RISK MANAGEMENT




Engineering / B07 - Eng / C13 - Massflow / Project Risk Management / 6. SLIDE 6: HOLDERBANK GENERIC RISK MAP

6. SLIDE 6: HOLDERBANK GENERIC RISK MAP

Engineering / B07 - Eng / C13 - Massflow / Project Risk Management / 7. SLIDE 7: CASE

7. SLIDE 7: CASE



Engineering / B07 - Eng / C13 - Massflow / Project Risk Management / 8. SLIDE 8: CASE

8. SLIDE 8: CASE

Engineering / B07 - Eng / C13 - Massflow / Project Risk Management / 9. SLIDE 9: RISK MODEL FOR CAPEX PROJECTS




Engineering / B07 - Eng / C13 - Massflow / Project Risk Management / 10. SLIDE 10: RISK MODELS – DEFINITIONS OF RISKS

10. SLIDE 10: RISK MODELS – DEFINITIONS OF RISKS

Engineering / B07 - Eng / C13 - Massflow / Project Risk Management / 11. SLIDE 11: RISK MODELS – DEFINITION OF RISK

11. SLIDE 11: RISK MODELS – DEFINITION OF RISK



Engineering / B07 - Eng / C13 - Massflow / Project Risk Management / 12. SLIDE 12: PROJECT CATEGORIES AND RISK MODELS

12. SLIDE 12: PROJECT CATEGORIES AND RISK MODELS

Engineering / B07 - Eng / C13 - Massflow / Project Risk Management / 13. SLIDE 13: RISK MODEL FOR CAPEX PROJECTS




Engineering / B07 - Eng / C13 - Massflow / Project Risk Management / 14. SLIDE 14: WHY RISK MANAGEMENT IN PROJECTS








Engineering / B07 - Eng / C13 - Massflow / Project Risk Management / 19. SLIDE 19: BRMP FOR SMALL PROJECTS






Engineering / B07 - Eng / C13 - Massflow / Project Risk Management / 23. SLIDE 23: BRMP FOR MEDIUM AND BIG PROJECTS

23. SLIDE 23: BRMP FOR MEDIUM AND BIG PROJECTS



Engineering / B07 - Eng / C13 - Massflow / Project Risk Management / 24. SLIDE 24: MEDIUM AND BIG PROJECTS

24. SLIDE 24: MEDIUM AND BIG PROJECTS

Engineering / B07 - Eng / C13 - Massflow / Project Risk Management / 25. SLIDE 25: PROJECT RISK MAP

25. SLIDE 25: PROJECT RISK MAP



Engineering / B07 - Eng / C13 - Massflow / Project Risk Management / 26. SLIDE 26: RISK DRIVER MIND-MAP

26. SLIDE 26: RISK DRIVER MIND-MAP



Engineering / B07 - Eng / C13 - Massflow / Business Risk Management for Projects (BRMP)

Business Risk Management for Projects (BRMP)May 1999Business Risk Management "Holderbank" Engineering Switzerland

1. CHECKLISTS AND FORMS FOR SMALL PROJECTS

1.1 FORM A1: Project: Kiln Shell Replacement Risk Identification (examples only)

1.2 FORM A2: Project: Kiln Shell Replacement Risk Identification (examples only)

1.3 FORM B: Project: Kiln Shell Replacement Risk Evaluation and Management (examples only)

1.3.1 Part of Scope / Project Stage: Pre-shutdown Activities

Engineering / B07 - Eng / C13 - Massflow / Business Risk Management for Projects (BRMP) / 1. CHECKLISTS AND FORMS FORSMALL PROJECTS

1. CHECKLISTS AND FORMS FOR SMALL PROJECTS

Engineering / B07 - Eng / C13 - Massflow / Business Risk Management for Projects (BRMP) / 1. CHECKLISTS AND FORMS FORSMALL PROJECTS / 1.1 FORM A1: Project: Kiln Shell Replacement Risk Identification (examples only)

1.1 FORM A1: Project: Kiln Shell ReplacementRisk Identification (examples only)

Generic Risks ØParts of Scope/Project StagesÚ

Project Parties ProjectOrganisation

Co-ordinationwith Production/Sales

Compliance

Pre-shutdownactivities

2) Lime stockpilemay be too low atthecommencement ofthe shutdown.4) The shutdownplan and schedulemay beinadequate.

Preparation ofused kiln section

Cutting, removingand shifting of kilnsections

12) Noise may begenerated duringshutdown activities.



Generic Risks ØParts of Scope/Project StagesÚ

Project Parties ProjectOrganisation

Co-ordinationwith Production/Sales

Compliance

Replacing,aligning,andwelding of kiln shell

11) Significantwelding will berequired and thismay pose a hazardor health risk topersonnel.12) Noise may begenerated duringshutdown activities.

Kiln bricking

Recommissioning,kiln lightup

Engineering / B07 - Eng / C13 - Massflow / Business Risk Management for Projects (BRMP) / 1. CHECKLISTS AND FORMS FORSMALL PROJECTS / 1.2 FORM A2: Project: Kiln Shell Replacement Risk Identification (examples only)

1.2 FORM A2: Project: Kiln Shell ReplacementRisk Identification (examples only)

Generic Risks Ø

Parts of Scope/Project StagesÚ

Time Cost Quality Commissioning

Pre-shutdownActivities

Preparation ofused kiln section



Generic Risks Ø

Parts of Scope/Project StagesÚ

Time Cost Quality Commissioning

Cutting, removingand shifting of kilnsections

1) The contractor'sequipment may notarrive in suitabletime.

Replacing,aligning,andwelding of kiln shell

1) The contractor'sequipment may notarrive in suitabletime.

8) The kiln may notbe cleaned prior towelding leading toproblems with theweld.

9) The compositionof the existing kilnmaterial is notknown and this willimpact on thewelding material tobe used.

10) Incorrectalignment of thekiln may occurleading to ongoingoperationalproblems.

Kiln bricking 3) Late delivery ornon-delivery ofrefractory material.

Recommissioning,kiln lightup



Engineering / B07 - Eng / C13 - Massflow / Business Risk Management for Projects (BRMP) / 1. CHECKLISTS AND FORMS FORSMALL PROJECTS / 1.3 FORM B: Project: Kiln Shell Replacement Risk Evaluation and Management (examples only)

1.3 FORM B: Project: Kiln Shell ReplacementRisk Evaluation and Management (examples only)

Engineering / B07 - Eng / C13 - Massflow / Business Risk Management for Projects (BRMP) / 1. CHECKLISTS AND FORMS FORSMALL PROJECTS / 1.3 FORM B: Project: Kiln Shell Replacement Risk Evaluation and Management (examples only) / 1.3.1 Part ofScope / Project Stage: Pre-shutdown Activities

1.3.1 Part of Scope / Project Stage: Pre-shutdown Activities

Risk andRisk Description

Existing Risk Treatment RiskRelevance

Proposed Risk Treatment

Signifi-cance

L,M,H

Likeli-hoodL,M,H

1) The contractor'sequipment may not arrivein suitable time.

M MConfirm that the equshipped and will arrive at site prior to thescheduled shutdown commencementtime.

2) Lime stockpile may betoo low at thecommencement of theshutdown.

Current kiln output is considered to besufficient to meet this target stockpileby the commencement of theshutdown.

A customer survey has beenundertaken to gauge expectedcustomer demands during theshutdown period.

M HIdentify and agree an alternative supplyand develop a supply agreement.

Continue customer surveys.

Ensure that customer silos are filled.

Ensure that ISO containers are availableand loaded prior to the shutdown.Consult with specialist in this regard.

Develop and implement a silomanagement strategy to ensure thatoff-specification material in silos at thetime of the shutdown is minimized.Schedule production to maximize limestockpiles at the start of the shutdown.

3) Late delivery ornon-delivery of refractorymaterial.

It is known that the overseasmanufactured refractory has beenshipped and is currently on route anddelivery details confirmed.

Local manufacturer representative hasbeen asked to confirm delivery date.

M LDo not start the shutdown unlesssufficient refractory is available.






Signifi-cance

L,M,H

Likeli-hoodL,M,H

4) The shutdown planand schedule may beinadequate.

An experienced contractor who hasundertaken other kiln shellreplacements elsewhere in the vicinityhas been engaged. This contractorhas contributed to the development ofthe plan. Owner also has experiencewith this contractor.

M LOngoing review of the shutdand schedule.

5) No formal safety planby the contractor and noformal transfer or risk.

The contractor employs experiencedcrews and has safely undertakensimilar jobs in the past.

M LDiscuss the option of development of asafety plan and work method statementsfor key work practices with thecontractor.

Follow through insurance and workers'compensation situation for the contractorwho is a foreigner. Investigate owner'sexposure to a major claim if an incidentshould occur.

6) Some of the work, e.g.debricking, may requirework in a confined space.

Site confined space procedure. Sitelockout procedure. M L

Confirm whether the kiln interior will berequired. Develop a specific procedurefor kiln entry during the shutdown.

7) The moving piece ofthe kiln may fall and bedamaged.

The strategy for moving the kiln piecehas been designed by the contractorto be suitable for movement withoutfailure.

H MCheck if crane support will be usedthroughout the process. If not, obtainfurther information from contractor onhow the moving piece will be supported.

8) The kiln may not becleaned prior to weldingleading to problems withthe weld.

M LEnsure that clear instructions are givenduring debricking to ensure kiln is cleanenough prior to welding.

9) The composition of theexisting kiln material is notknown and this will impacton the welding material tobe used.

All likely materials required to be usedin welding are known to be available. M L

Undertake sampling and analysisoon as possible once the kiln material isavailable for sampling.

10)Incorrect alignment ofthe kiln may occur leadingto ongoing operationalproblems.

The contractor is expert in undertakingkiln shell replacements.

Owner's personnel will confirmalignment prior to commencement ofwelding (included in work schedule).

H LNo additional risk treatments arerecommended.






Signifi-cance

L,M,H

Likeli-hoodL,M,H

11)Significant welding willbe required and this maypose a hazard or healthrisk to personnel.

Contractor expertise and existingwelding procedures. L L

Ensure that contractors are briefedregarding owner's requirements inrelation to welding.

Ensure that ID fan is used to ventilate theinterior of the kiln.

12)Noise ma y begenerated duringshutdown activities.

There is a restriction of night timeoperations at site.

Owner's personnel is well aware ofnoise issues and takes control actionto reduce noise.

A complaint procedure is in place fordealing with environmentalcomplaints, e.g. noise complaint.

L LNo additional risk treatments arerecommended.

About the "Holderbank" Cement Course 2000 CD-ROM

About the "Holderbank" Cement Course 2000CD-ROM

The "Holderbank" Cement Course2000 CD-ROM contains the full text and graphics of the sevenbinders distributed during the course.

• Material Technology I

• Material Technology II

• Material Technology III

• Process Technology I

• Process Technology II

• Process Technology III

• Engineering

The CD-ROM can be read like a book, page by page, or you can take advantage of the advanced



features of the software to quickly navigate to a specific binder, chapter, document, or section withinany documment. If you are unsure of where to look for the information you require, there are extensivesearch facilities to allow you to locate the appropriate section.

This CD-ROM was produced during February - May 2000 by “Holderbank” Management andConsulting Ltd., Corporate Training.

♦ Department manager: Dr. Walter Baumgartner

♦ Project manager: Fred Aubert

♦ Contents provided by the following departments of “Holderbank” Management and Consulting Ltd.:

• Materials Technology (MT)

• Mineral Components (MIC)

• Product Development and Applications (PDA)

• Process Technology (PT)

• Maintenance (MTC)

• Holderbank Engineering Switzerland (HES)

♦ Project administration: Michèle Stark

♦ Project consulting: ETV Software Engineering S.A., Geneva, Switzerland.

♦ Acknowledgments

• Mr. Fred Aubert. As Technical Training Manager of Coprorate Training in HMC took care of therelations with the authors and gave many inputs which helped substantially to define the project.

• Ian Bennett. The advice and consulting work given by Mr Bennett from SE was of immensevalue throughout all phases of the project.

♦ Copyright notices

• © “Holderbank” Management and Consulting Ltd., 2000All rights reserved

• Interface controls & Indexing and Retrieval Engine Copyright © 1998 Open Market, Inc. Allrights reserved.

• Contains data security software from RSA Data Security, Inc. Copyright © 1998 Data Security,Inc. All rights reserved.

• Indexing and Retrieval Assistant for dictionaries. Copyright © 1998 Soft Art, Inc. ® All rightsreserved.

• ImageStream® Graphics & Presentation Filters Copyright © 1991-1998 Inso Corporation, Allrights reserved.



Endnotes

1 (Popup - Popup)

1 Paper presented to the IEEE Cement Industry Technical Conference, Salt Lake City, USA, May 19th-22nd 1986, andpublished in “Holderbank” NEWS 6 (1986)

Cement Industry Engineering-Holderbank Course(2 of 2)

Documents

Transcript of Cement Industry Engineering-Holderbank Course(2 of 2)