WEA1-BuckHolz Relay

It is installed between conservative tank and main tank. It is purely mechanically operated relay.

In minor fault relay is operated by gas In severe fault relay is operated by pressure of oil Two

"floats" which control the position of magnet and indirectly operate the switches. Upper float for

alarm Lower float for automatic tripping of transformer.

It protects only due to the internal fault of a transformer.

Tap Changer:

There are two types of tap changer

1. On load tap changer (NTDC)

2. Off load tap changer (distribution)

Regulate the voltage

Switch Gear Lab

Grid Station:

Without disturbing the frequency, change voltage level from one value to another.

Bus Bar schemes

1. Single breaker single bus bar:

Line/(earth switch/isolator) line isolator/breaker/CT/Bus bar/ CT/Breaker/ (lightning

arrester+transformer+lightning arrestor)/ incoming breaker/ CT/PT/Bus Bar

2. Single breaker Double Bus bar: ->Two bus bars with two breakers

line/ earth switch/isolator/breaker/CT/PT with each bus bar/ (Double breaker double bus bar)/

CT/Breaker

3. Double breaker double bus bar

4. One and half breaker scheme 3 breakers and 6 isolators on one bay (two bus bars). Each

breaker have two isolators. It is beneficial whenever there are three incoming lines.

CT: over currenr

Differential relay: its zone is between incoming feeder and outgoing feeder. It works on the

basis of difference between two current values.

WEA1-Lec2-Power System

Generation voltage is between 5Kv to 25KV due to limitation.

WarSac generating voltage is 6Kv, with capacity 243MW

Tarbella 13KV and 18 KV with capacity 3500MW on Indus River. We can get 10%

overrated generation with recorded value 3700MW, connected to 500KV with RawAt,

Muhamdi, Gatti, Sheikhupura.

ghazi brotha 1450MW

Dhaso 4320MW

Nelum jehlum 965MW

->Installed Capaciry

1. Thermal 4811MW

Muzaffar Garh

Bin Qasim

Jamshoro Lalpir 362MW

2. Hydal 6461MW

3. IPP's 6365MW

4. Nuclear 462MW

5. WindPower 50MW (6m/s is minimum speed for generation of wind energy)

6. Solar 5200MW (1KW/m2 is trapable energy)

Type of feasabilites

1. Technical feasibility

2. Economic Feasibility

EHV/Primary Transmission benefits

EHV/Primary Transmission, has three benefits

1. Losses reduce

2. Conductor size reduces

3. Power transmission capability increases

P @ ((Vs)(Vr)(Sin&))/XML

P @ (Vs)(Vr)

P@ V2

if voltage is increased by 10 times, power transmission capability increases by

100 times.

Transformer Ratings:

220Kv/132KV is 250-160MVA

132/11KV is 20-26MVA

11/220 is 100KVA

Types of Breaker on Quenching media

1. SF6 breaker

2. Oil breakers

3. Vacuum breakers

4. Blast air breakers

Generators

Generators can give both type of powers

1. Active power

2. Reactive power

Active power and frequency is controlled by Prime mover

Reactive power and voltage is controlled by exciter

Classification of transmission line

Short < 80Km

Medium 80km-240km

Long greater than 240Km

Types of Reactors

1. Series reactor

2. Shunt reactor

Capacitor is installed where power factor is bad. In transmission line, VAR is in excess

so we have to absorb them so we install "Shunt Reactors"

o 500KV 12 grids

o 220Kv 30 grids

o Lag and Lead are basically "time difference".

o Delta: 3 time power capability Harmonic trap

o Star insolation economy (generator's winding is connected in Star)

EA1-Lec3-Analogue Simulator lab

Mimic Diagram:

Drawing dream on control panel is called mimic diagran

Power simulator:

Power simulator is define as, replication of original power system on which various normal and

abnormal conditions can be demonstrated.

Normal conditions:

1. Rated Voltage

2. Rated frequency

3. Balanced Load

4. Maintained stability

5. Power generation greater than demand

Abnormal Conditions:

1. Short circuit (positive sequence, negative sequence, zero sequence)

2. Switching surges (Jerk)

3. Lightning over voltages (LOV)

4. Fehranti effect (no load, line should be atleast medium) We install shunt reactor at

receiving end to overcome this problem.

5. Mall synchronization

Synchronization: Process of connecting two different sources, through sncronizing breaker

meeting conditions ( same voltage, same frequency, same phase angle, phase sequence.

Synchronizing panel:

1. Dual volt meter

2. Frequency meter

3. Snchronoscope/phase displacement indicator

In field a relay is used called "synchro check relay".Only than

Permeseable ranges:

Difference of voltage for 132KV is +-10%

Difference of voltage for 220KV is +-5%

Difference of voltage for 500KV is +-3%

Difference of frequency is 0.1%

Difference of angle is 30 degree.

Bad effect: Instantaneous voltage difference due to which circulating current will flow and

will damage the insulation.

Every generator has a Generator's capability curve, which tells it will share how many MW and

will deliver how many VAR.

Relay types

First generation electro Mechanical Relay

Solid state relay/Second generation relay

Microprocessor based relay /Third generation relay

Generator's Relay

1. Generator differential relay

2. Over current over load relay

3. Unbalance load relay / negative sequence

4. Under frequency relay

5. Stator earth fault relay

6. Under excitation relay

7. Reverse power relay

8. Rotor earth fault relay

9. Voltage drop relay

10. Voltage rise

Transmission line relay

Impedance/Distance relay

Whenever there is a fault, at that time voltage decreases.

WEA2-Lec1-GSO-Auto Recloser

"The process of automatic closing of a circuit breaker, after that it opens." 3 shoots, after that if

fault persists it locks out, otherwise if fault is temporary, it restore the system.

Circuit:

Two portions,

1. Control box operate on 24V

2. Interruption

Types:

1. Fast auto reclosers

With in 0.3 sec

Single shoot

Used in larger systems, bcz if it remain for a long time, synchronism can be lose, and

system collapses.

Time Designation"

2. Delayed/Low auto reclosers

More than 1 sec

3 shoot First try after 5 sec of fault, second try after 8 sec of fault, third try after

10 sec of fault. There is also a reset timer

Install on 11KV feeder Tranches and also on the beginning of each feeder

Tr CBt Arct Fc-Zero 1st shoot

WEA2-Lec3-BatteryRoom

Battery: ->Two or more cells are called battery. ->Batteries should be connected in series. -

>Weather effects the efficiency of battery, if temperature increases by one degree specific

gravity of a battery decreases by 3 points and vice versa. ->132KV and 66KV grid stations need

the battery of 110V(55 cells) 200KV and 500KV grid stations need a battery of 220V(110 cells).

->Ratio of acid and water in battery is 1:4. ->Over current damages the plates and same effect is

due to excess of acid. ->When voltage is below 1.7V than it should be provided with "Booster"

and when voltage reaches to 2.33V it should be change to "Floating" condition.

Specific gravity criteria: 1.240-1.204 efficient/well charge 1.2002-1.204 well charge Less than

1.2002 poor charge

Important parts: Connecting strips Pilot Cell(poor in voltage and also in specific gravity) Gases

wind plug

Precautions of Battery Room: 1.Analyzer should be used at the time of entrance in the battery

room. (Analyzer senses the gas) 2.Exauat fan should be in running position during 24 hours

3.Walls paint with anti acid paint 4.Rubber/Venyl type mat should be on the floor 5.Apren

should be with the worker 6.Brass brush should be with the worker 7.Glasses and gloves

Availability in Battery: 1.Hydro meter 2.DC volt meter 3.Thermometer 4.Petroleum jelly or

Vasline 5.Distilled water

Purpose: 1.Protection for tripping of the relay (coil) 2.Emergency light in control room

WEA6-LEC1-Insulators

Objective: To determine the flash over voltage test 11KV pin type insulator in case of Dry and

wet conditions.

Flash over: An electrical discharge passing through the air, between connecting part of

insulator(pin, conductor) in the form of spark/arc when high voltage is applied.

Puncture: An electrical discharge passing through the insulator's body itself.

HT insulator: Disc type Pin type

LT insualror: spool type strain type

Apparatus: 1.HV control desh 2.Two, Test transformer S/P 220V/100KV AC 3.V, connecting

(4)K, connecting cup 4.Measuring capacitor 100pf, 100KV Ac 5.Earthing switch 6.CM,

measuring capacitor 100pf, 100KV AC 7. 8.RL charging resistor 10M ohm 9.Connection leads

10.Co axial measuring cable 11.Test object

Reasons of Flash over: 1.Lightning stroke 2.Over voltage 3.Permanent fault (phase to phase,

phase to ground) 4.Transient(switching) surges

Creeping distance: Distance between the pin of insulator and line. As creeping distance

increases, flash over value increases too.

Flash Over voltage Wapda Standard: 1.Pin type 11KV 70KV in case of dry condition 40KV in

case of wet condition 2.Disc type 11KV 80KV in case of dry condition 50KV in case of wet

condition 3.Spool type 25KV in case of dry condition 15KV in case of wet condition 4.Strain

type 35KV in case of dry condition 18KV in case of wet condition

Puncture Voltage Wapda Standard: 1.Pin type 11KV 95KV 2.Disc type 11KV 110KV

Test voltages: Pin type, 65KV for within one minute stand Disc type, 75KV for within one

minute stand

Load on insulator: 1.Electrical load (Voltage) 2.Mechanical load ( weight) 3.Atmospheric

variation transients (summer, winds, blow)

Materials: 1.Porcelain covered by smooth and hard glaze of brown color 2.Pin is made of

galvanized mild steel

WEA6-Lec2- Tools and Plant (T&P)

T&P 1.Proper T&P 2.Assigned work

Parts 1.PPE(personal protective equipment) 2

WEA6-Lec3-Cable

Fault detection: Overhead->we petrol Underground->Pulse reflection instrument

Megger: 1.To check insulation 2.To check continuity

Open circuit: Show max value, and tell us the point and nature of fault Short circuit: Intermittent

type of fault (weak insulation fault): "Burn Down Unit", we apply upto 18KV, in this way,

insulation start to burn at the point of weak insulation.

Types of joint in Underground cable: 1.Termination joint (*indoor termination 2inch Per Kv,

outdoor termination 3 inch per KV) 2.Straight joint (Sleeve) 3.Tee joint (Gfw switches)

Types of HT Cables in underground 1. 3/C and S/C PVC , X.LPE U/G cable 2/0 AWG 110A 2.

3/C and S/C PVC, X.LPE U/G cable 4/0 AWG 215A 3. 3/C and S/C PVC, X.LPE U/G cable

500MCM 380A 4. only S/C PVC X.LPE U/G cable 1000MCM 580A

Methods of jointing: 1.Heat shrinkable method 2.Cold shrinkable method 3.Compound method

4.Tapped method

Types of LT cables in underground 1. 2/C or 4/C PVC insulated cable 7/0.052" and current 32A

2. 4/C PVC insulated cable 19/0.052" and 77A 3. 4/C PVC insulated cable 19/0.83" and 115A 4.

4/C PVC insulated cable 37/0.83" and 177A

Parts of HT cable 500MCM S/C PVC XLPE U/G: 1.Conductor carries current 2.Conductor

strand shielding To fill the air gaps between conductor and in isolation, and also cinfine the

circulating current 3.Insulation (XLPE) prevention from current leakage 4.Semi conducting tape

To distribute the electrical stresses evenly produce, when cable is energized. 5.Cooper shielding

tape Services as a drain to ground 6.Cotton tape To hold the mettalic shielding tape in place

during manufacturing and remove sharp edges of the copper shielding tape 7. Cable jacket To

protect the table against moisture, heat and physical damage.

Objective: To locate the cable fault by means of Pulse Reflection in instrument LMG 4000

Formula: 2D = V*t D = (V/2)* t Under test cable : 7/0.052" Limitation up 20,000 meters or

20Km ->This device has an error of 1m to 3m

"Audio frequency unit for pin point

WEA7-Lec1-Jointing of conductor

Types of joints:

Full tension joint: Span is a distance between two poles. If conductor breaks at the point of

dip(tension point), than we apply tension joint. 1.Splice joint For copper stranded conductor

2.Twisted sleeve joint For copper conductor having one wire 3.Single sleeve joint For Rabbit &

Gopher (ACSR) Wasp, Ant & Gnat (AAC) 4.Double sleeve joint Only for ACSR Dog 5 Repair

sleeve joint All ACSR

Non-Tension joint: Where there are dead ends and no tension in the wire. 1."Line tap

compression connector" for permanent jumpers of various line conductor at various places

2."Parallel groove connector", for temporary jumpering of various line conductor 3."U clamp"

used at each end of LT line (dead end of wasp conductor) 4."Service and line tap connector" for

permanent connection of consumer's service with line

Splice joint: 8, 7, 7, 6, 6, 5 turns on each side

Disadvantages of splice joint 1.Gape remains between strands 2.Sparking, heating effects 3.It

may breakdown again

Information on sleeve: There are three things mentioned: Conductor name Use tool to press MD-

6 Dye number W-249

"Oxide inhabiting compound" in sleeve, which prohibits rusting

Double Sleeve joint: Dog: 13 strands (7 steel, 6 aluminum) Sleeve Dye number: 248 (4 press)

Advantages of Proper joint 1.Have good electric contact 2.Have requires tensile strength 3.Have

no weather effect

WEA7-Lec2-transformer

Transformer in No-Load: Two type of current flows in primary, 1.Inductive current for the

magnetization of coil 2.Resistive load as coil has its own resistance.

Types of Loads: Three types of electrical loads 1.Resistive 2.Inductive 3.Capacitive

Power factor: Power factor is inversely proportional to angle between voltage and current.

Actually we are increasing the power handling capacity of the system, whenever generation

remains the same. We can achieve unity power factor by increasing capacitance in the system(up

to a certain value where capacitance totally nullify the inductance), but cost/benefit ratio is not

economical. So our standard is 0.9 in Wapda.

Resistive load on transformer: Resistive load improves the power factor Resistive load creates

voltage drop Resistive load increases losses Losses: losses@ I2

Inductive load on transformer: Current increases Voltage drop increases losses increases Power

factor gets poor

Capacitive load on transformer: current decreases power factor improves

Formula to find value of Capacitor for desired power factor:

KVAR(C) = P(KW)*(tan@1 - tan@2) where, P(KW) is rated load @1 is current angle from

current power factor @2 is required angle from required power factor

WEA-Lec3-Dielectric strength of transformer oil (IEC

296)

Oil name: Hydro Carbon Mineral oil Dicholoro difluoro ethyl benzene

Purpose: 1.Insolation 2.Cooling 3.Flash point (140'C)

Wapda standard for 11KV: ->30KV for one minute with the gape of electrode 2.5mm ->Raising

the voltage at the rate of 2KV/sec

Samples from transformer oil: 1.Top (water vapours) 2.Mid (light impurities, cotton tape small

wooden piece, varnish, wire enamel, paint) 3.Bottom ( Carbon)

Air bubbles: Air dielectric strength is less than transformed oil, so first remove air bubbles than

apply test

If result is less than standard: (Oil is sent to "Reclamation workshop", which is actually a

transformer workshop. There is a "Dehydration plant" over there, in which transformed oil gets

clean.

Vector group(nameplate): If we need to connect two transformers in parallel, than there vector

group should be same. Wapda standard is DY11. By changing internal connection, vector group

changes

WEA8-Lec1

Core Winding

Eddy current in core (hysterisis loss) load current in winding

Losses should be within specified limits (standards defined by IEC or BSS or ANSI or VDE ) .

Wapda follows IEC. If these losses are beyond limit, than transformed would not be purchased.

IEC : International Electric Commission BSS: British Standard ANSI: VDE:

Tests: Core losses/Iron loss/ No load loss: Open circuit test Copper losses: Short circuit test

****Open circuit test*****: This test is used to measure "core losses" HT side open LT side is

excited and is connected with ammeter, voltmeter and wattmeter No load current is flowing in

LT winding which produces magnetic field and heating effect. 1.Reactive component of current

produce magnetic field 2.Active component of current produce Heat Due to sinusoidal current

alternating magnetic field produces which contracts and expands with time. So, this changing

magnetic field produces Emf.

Eddy losses: The same magnetic field links with the core and an emf hence a current known as

"eddy current" flows, which produce losses. This loss can be minimized by using insulating

sheets.

Hysterisis loss: Due to polarity change in core (reversal of magnetism). Our frequency is 50Hz

but change in polarity of domains is 100Hz. Due to this fast changing, their remains some

magnetization in the core and also a sound ( magnetostriction) is produce in the transformer due

to this phenomenon.

Material of core: Silicon steel (Its area under the curve of current-magnetization curve is less, so

hysterisis losses are less)

Why we are exciting LT not HT in No load test: 1. Less voltage is require for excitation instead

11KV main power supply would be required 2.Problem in measurement of high voltage

3.Protection in handling

No load current in Three phases: Three currents in three phase of three phase transformer would

not be equal. Central phase current would be less than side phases, this is because of the

symmetry of three coils in a transformer.

Standard readings: 10KVA 15KVA 25KVA 50KVA

WEA8-Lec2-Tying/Binding of Conductor

Aluminium Annelead tie wire Size= 4mm dia

Types: 1.Top tie 2.Side tie 3.L.T tie

Conductor Top Tie Side Tie Panther 13'. 12' Osprey 12'. 11' Dog 8'. 7' Rabbit 7' 6' Gopher 6' 5'

Wasp 7' Ant 6' Gnat 5'

Top Tie= 2+3+2+1+1+1+2=12 Side Tie= 2+3+1+1+1+2=10 L.T Tie = 2+3+1+1+1+2=10

HT insulator: Pin type Disc type (dead end)

LT insulator: Spool/shackle type Strain type (dead end)

(Armour rod was used before, for the protection of conductor) ->Transformer earthing resistance

is less than 5 ohm ->Consumer meter resistance is 10 ohm

WEA8-Lec3-Energy Meters

Meter records electrical energy in KWh.

Principle: Electromagnetic induction

Parts of Meter: 1.Potential coil 2.Current coil 3.Spindle Jeweel Disc 4.Permanent magnet 5.Dial

Truch 6.Name plate 7.Terminal block 8.Base plate 9.Glass window 10.Meter cover

Mechanism: 1.Driving mechanism 2.Braking mechanism 3.Recording mechanism

Testing method: 1.Long period test 2.Short period test

Long period test/ Energy Comparison method: In the long period test energy recorded by

"observation meter" and energy recorded by "Correct method". Compare the both recorded

energies and the %age error is find by the following formula: %error= ((Eo - Ec)/Ec)*100 Eo=

Energy recorded by observation method Ec= Energy recorded by correct method

2.Short Period Test %age error calculated by the following formula: %age error = ((Tc -

To)/To)*100) Tc = Time calculate To = Time observed

Tc= (3600*rev)/(Load KW*meter factor) if meter is CT operated, then

Etc=((3600*rev)/(load*M.C))*M.F

M.F= Ct ratio/ meter current ratio

Check: 1.if Tc>To then meter is fast 2.if To>Tc then meter is slow

Wapda standard tolerance: +-2.5% to +-3%

TOU meter: The TOU static meter is the first of a new generation of electronic meter that is

designed by advance Computer and electromagnetic Compatibility Technology. Meter is fully

static without any moving parts. And its performances are conformity with Wapda specification

and relevant international standards. 3-phase multi rate / multi function (TOU/TOD) meter

designed to meet the high accuracy and multi tarrif requirements.

Parts of meter: 1.Vs = voltage sensor 2.Cs = Current sensor 3. DSP=digital signal processing

4.MCU=micro computer unit 5.IC's 6.CT's

Salient characteristics of an Electromagnetic meter: 1.High functionality 2.High accuracy 3.No

tilt error 4.Susceptibility to extreme environments 5.Susceptible to Electromagnetic

compatibility / interference issues 6.Max expected life of 15 years

S/P static meter LCD display: ->serial number ->Total energy (kWh) –

WEA9-Lec1-Providing Temporary Earthing to the Line

Need: 1.For the safety of working staff/to avoid mishap 2.To avoid undue/wrong operation of

any equipment 3.To do the job efficient being safe/to achieve better workmanship

Source of Re-Energized of any Dead line: 1.Back supply a) operation of Generator of any

consumer b) Double feeder supply c) Ring man system (RMS/RMU) 2Due to induction of any

other line passing over 3.Due to lightening 4.Break down of any other feeder passing over 5 Due

to tree branches hanging between two feeders.

Where tempo earthing: Both side of working zone

PTW is issued to lineman, than same person have to cancel it. 11KV earth tester to check the

status of line Source side(grid) has to earth first, than Load side(working side) has to earth After

work T&P is removed PTW is cancelled

WEA9-Lec2-Induction motor, power factor improvement

Stator is provided with three phase ac Rotor is short circuited

Power factor: Power factor at no load is very poor 0.1-0.2 At normal load Power factor is 0.5-0.6

At max load power factor is 0.8-0.86

Why not to run on no load? Because at that point rated current is flowing and if due to some

reason voltage drops to some value than at same value motor will draw more current

Normal load: 60% to 80% At this load power factor is 0.5-0.6

Power factor: ->Cosine of the angle between voltage and current waveform. Angle depends upon

nature of load. ->Ratio of active power and apparent power ->Ratio of resistance and impedence

When we apply the voltage at no load, than the voltage is only used for magnetization, it means

there is some kind of inductive load, (no resistive), so the system power factor at no load is poor.

Motor is drawing two types of current, 1.Working current 2.Magnetization current

Equipment use for pf improvement: 1.Capacitors 2.Synchronous condenser: Basically its

synchronous motor, running in overexcited mode with no load. 3.Phasor bansers

Delta and star: Capacitor required in star is three times capacitor required in delta. C(star) =

3*C(delta) But, In distribution side it is beneficial to use in Delta In HT side(feeder) it is

beneficial to use in Star(Less in isolation is required, because voltage in star is less than voltage

in delta)

Fuses required: Up to 5horse power direct starting is used and fused are required for double

rating

Greater than 5horse power motor "star delta starting" method is used, and fuses size need to be

1.5 times of motor rating.

Shuttling of KVAR: Capacitor stores KVAR from the source and then provide it to the system

whenever polarity changes. These KVAR are stored in the form of electric field. Same shuttling

phenomenon occurs in inductor, and KVAR are stored in magnetic field.

WEA9-Lec3- Transformer turn ratio

When applying "D" some of the turns get shorted. The D of that coil drops again and again when

some turn of transformer coil get short, the other two coils (D's) remain stand by.

WEA10-FESCO Transformer Workshop

Categories of repairing: 1.Major 2.minor Transformer came from SDO or Exion 3.Major

repairing from FESCO store

Dehydration: for 72 hours 1.Oil is sent to dehydration plant through pumps Oven: Winding is

kept in oven, to remove moisture

Washing section: Tank is sent to this section to clean it, there may be blockage of carbon in

pipes. Castic soda 90'C to 110'C 72 hours

Dehydration plant: 1.Oil gets clean 2.Dielectric strength recovers

Oil test: 1.Dielectric strength 30KV with one minute stand maintaining 2.5mm 60KV for new oil

2.Moisture test Absent 3.Specific gravity 0.895 4.Flash point 140'C 5.Viscosity 40 CST (Centi

Stroke) 6.Delta Tan test For power transformer

Winding section:

Paint section: Smoke gray for outer side Red oxide for inner side

Transformer test: 1.Winding resistance R=? 2.No load test Iron loss test 3.Full load test

converted at 75'C Copper loss 4.Induce voltage insulation test 5.Desperate source over voltage

with stand high voltage test 6.Turn ratio test voltage ratio 7.Air pressure test leakage test 8.Bird

protection test prevent birdage 9.Tin coating & other allied test on connector 10.Visual and

dimentional 11.Oil test of transformer oil quality

Winding section: After design testing 12 transformer g For insolation we use, Press pan paper

Press ply sheet

WEA11-Lec1-Steam Power plant

Advantages of simulator:

Response according to actual plant

Check the response 10 times faster than actual time

Back train provision from 1 mint to 5 mint

Snapshots, from where we want to start training we can start from that point

Synchronization of plant is the issue in actual plant, so here we can get trained easily

Mall function faults (95 in number)

Our simulator specifications:

Balanced drop furnace

Tandem compound turbine

Water tube boiler

37-40% efficiency

Components:

Boiler

Steam Turbine

Generator

Panels:

Fuel

air section

Water steam panel

*****Boiler*****

Color scheme:

Dark green color for "pure water"

Light green for "Raw water"

Dark red for "dry steam"

Light red, for "wet steam"

It is also called "steam generator”.

Riser tubes

Steam is generated in "Riser tubes" and is stored in Steam drum.

Down covers tube

"Down covers tube" just outside the body. Natural circulation of water in riser tubes and down

covers"

Types:

Fire tube boiler

Fire in the pipes, water outside

Water tube boiler Water inside the pipes, fire outside

Fuel:

Propane Just for ignition of main boiler, as a pilot flame

Crude oil (Bunker C)

Light oil

Burners:

16 burners

4 elevations (4 burner on each elevation)

Corner firing

Types of furnaces:

1. Pressurized furnace

2. Balanced drop furnace

Fans:

Forced dot fan(2)

Induced dot fan(2 fans)

Up to 50% load one FD fan is enough Pressure inside burner is balanced, minus 1mili bar

vacuum.

Flue gases (200'C) Rotary type air heater to heat up the gases.

Burner position:

Changing the position of boiler is called "tilting". If temperature is not rising than do not change

the fuel injection but apply tilting

*****Turbine*****

Types:

1. Impulse turbine

2. Reaction turbine

Portion of Turbine:

1. High pressure turbine (HP)

2. Intermediate pressure turbine (IP)

3. Low pressure turbine (LP)

(These all have same speed, mounted on the same shaft)

Quality of steam to run turbine:

Temperature not less than 320'C (minimum)

50 bar pressure (minimum)

165 bar (normal)

540'C (normal)

WEA11-Lec2-Steam power plant

How we get feedback that load is greater than generation??

Voltage dips Frequency falls

Frequency is controlled by hydal plants not by thermal plants.

Hydal:

Thermal:

Two types of it,

Steam turbine

Boiler

Turbine

Generator

Gas turbine

In thermal plants we cannot control frequency, because in short time we cannot inject

more heat, so if we do so, than steam gets from dry steam to wet steam, on which we

have a protection, so unit trips.

*****Steam Turbine*****

Quality of water:

Demy water/Demineralized water.We install chemical plant. Get water from canal or tube well

(high conductivity). Chemical dosing by sulphuric acid dosing and got demy water. If we are

running the plant for the first time, we take water from "feed water tank". Feed pump 15-20 feet

high. Boiler drum is filled by it

Deaerator:

Showering from one side and heat from other side, so that components remove from it.

Hydrazine, phosphate used for dozing.

Starting of boiler:

Not immediate flaming in order to avoid explosion due to the storage of gases.

Purging System:

A system to remove gases in the boiler. For this two type of fans 1.Forced draft fan Suction is

from Hot reservoir or hall 2.Induced draft fan Produce vacuum in the furnace Air fuel ratio is

maintained in ratio 1:10

After forcing boiler is fire up. Now we have to provide heat so that 1' rise in temperature in one

minute in order to avoid "hammering"

Type of Boiler start:

1. Cold start (Less than 150'C)

2. Warm start (150'C to 250'C)

3. Hot start (greater than 250'C)

Waste water temperature:

Its temperature should be 7'C.

Auxiliary steam:

We heat up the turbine before feeding steam to it. In turbine the upper and lower part shouldn't

have its temperature greater than 50'C.

Turbine drain system:

All heat that is condensate is sent to "Hot well".

Rolling of turbine:

Before rolling check the following conditions, Turbine heating Lubrication system Hydrogen

cooling Seal oil system

Turbine speed limits:

500rpm for 30 minutes 1000rpm for

WEA11-Lec3-Steam Power

Tandem compound turbine:

Turbine having more than one cylinders

*****Water Cycle*****

Water should be clear up to 1ppm (pound per million) 1100 ton per hour water is

required, so we recycle the same water.

Steam is condensed in "condensator" having temperature 50'C to 80'C 1 or 2% water can

be lost, so regular compensation is needed.

When plant is not running, and we have to run the plant, than the cycle is as:

Water is filled in "Hot-well" which is for the storage of condensate water, where water

level is 200mili meter.

"Condensate pump" A and B, one would work other will be in standby.

"Polisher" checks whether the water is pure or not, if not, it removes impurities.

"Gland steam condenser", in which there is a heater, which warms the water, and is the

first step of per heating.

"Deaerator pump" which pumps the water.

"LP Heater" which again rises the temperature, here steam is used for heating purpose

which is called steam bleeding/steam extraction.

"Deaerator" which removes air from the water, because air creates hammering in the

pipes. Steam is injected at certain angle and keep away the air with it.

"Deaerator storage tank", in which level of water is 2m.

Three "Boiler feedback pump" with pressure 200 bars, one runs at 50% load, second

started work at full load, these two have motors, other which is in standby is run by mini

turbine.

"HP heater" which further heats up the water.

((5 steam lines, two are from LP turbine, two are from IP turbine, and one from cold

reheat line. Two are used in LT heater, Two are used in HP heater, one is used in boiler

heat pump (mini turbine pump)))"

Regulating valves, (low load valve, full load valve), 250'C.

After that water goes to economizer gaining temperature 280'C and then to Boiler drum.

Now this is warm water and easily converted to steam.

Down comer tubes:

Just outside the boiler, from which water comes from boiler drum into the boiler.

Riser tubes: Steam is made in Riser tubes.

Note: 7 stages of preheating of water before going to drum

WEA12-Lec1-Combine cycle

It has following parts, 1.Gas turbine 2.Heat recovery steam generator 3.Steam turbine

*****Gas Turbine*****

Fuel:

HSD oil/diesel

Furnace oil/crude oil

Natural Gas

Components:

1. Compressor

2. Turbine/Combustion chamber

3. Generator

Compressor:

To compress the natural air, which rises the temperature of compressed air. Air is cleared

through filters because Dust and moisture have to remove, which can accumulate on blades,

results in unbalance of weight causes vibration.

Two types of blades use in turbine,

Rotatory blades

Stationary blades

Fit in diapharam in the form of segments.

Three stage gas turbine Four stage gas turbine

Barings:

Two type of Barings,

1. General barring

2. General thrust barring

Barings are lubricated from below, because in static condition shaft can touch the white

metal. Lubrication oil has the function of "cooling, reduce friction, center the shaft".

General:

A part of shaft which rotates within the barring is called General.

White metal:

If anytime lube oil system fails, than white metal is a protection of the shaft. Shaft is made of

hard metal and barring is made of soft metal, so if shaft hits against the white metal, it is saved

from damaging.

Gas turbine is designed on 30'C and its Exhaust temperature is 500'C. Lower the ambient

temperature lower the exhaust temperature, and hence it can take more load. To control the

temperature, eight "Thermocouple" are installed. If temperature rises, the machine left the load

and if temperature is not controlled machine gets trip. If temperature is below 15'C than

efficiency reduces. In normal days we have ambient temperature of 45'C so an inter-cooling

system "Evaporator cooling system" is introduced.

*****Heat recovery Steam Generator*****

Types:

1. Horizontal

2. Vertical

Parts:

Economizer

Evaporator

Super heater

Economizer->Boiler drum->Evaporator->Boiler drum->Super heater

In steam drum there are "steam separators" which desperate steam from water.

Source:

1. Direct from waste heat

2. Supplementary

WEA12-Lec2-Boiler and turbine terms

*****Boiler*****

1600'C is the temperature of boiler 300'C is the temperature of steam

Balanced Draft furnace

Pressure is not too high not too low

Furnace Probe:

Its function is of temperature measurement. It should be in before start, so that we get the

knowledge whether or not there is any fire in the furnace before

Super Heater:

Three super heaters. It has so many tubes which increase the surface also wet steam to be there

for some period. They convert wet steam to Dry steam.

D-Super heater:

It is connected with the coils of super heater and give the control to control temperature. These

have interlocking and don't open until pressure is 70bars. It has the disadvantage that if there is

any leakage than injection of pure water will be there and temperature reduces without our

requirement.

Economizer:

Its for preheating of water going into drum. Efficiency of the plant increases.

Steam type air per heater:

Initially air is warmed with the help of steam.

Rotary Type Air preheater:

Flu Gas recirculation fan:

They recirculate the flue gases in the furnace. They suck gases from the exhaust end and

discharge that warm air just above the burners, so fuel reduces.

Fuels:

1. Propane (yellow color)

2. Bunker C (Brown)

3. Light oil (orange)

When plant is just going to start, start it with "light oil", if bunker C is just ready and we

cannot use it until drum pressure is 40 bars.

Bunker C has heating quality (Btu per pound) greater than light oil, so we cannot slow

heat with bunker C.

Why slow heating of boiler is essential??

Because sudden heating causes "Thermal Stresses" of metal tubes, than cracks in the next stage

and ultimately damage the tubes.

If a fuel is in liquid form than before burning we have to "atomize" it. In atomized form

fuel is almost in gaseous form, than "pilot burner" will burn the fuel.

Methods of atomization:

1. Mechanical atomization

High pressure pumps discharge the fuel from the nozzles. Bunker C is atomize in this

way.

2. Air atomization

WEA12-Lec3-Steam cycle

Cycle:

Drum to primary super heater

Primary super heater to D-Super heater

D-Super heater to Secondary super heater

Secondary super heater to D-Super Heater

D-Super Heater to tertiary super heater/ final super heater, where it is converted from

Wet steam to Dry steam/super-heated steam/ live steam, having temperature 540'C and

165 bars

HP turbine 320'C pressure 35 bars, than it again goes to furnace for re heating

Furnace has "Primary re heater" than it goes to "Secondary re heater" than it goes to "IP turbine"

than to "LP turbine"

Main steam drain:

Main Steam safety valve (mechanically operated):

Operated at 182bar

Electrometric release valve:

178bar

HP turbine bypass line:

If pressure is beyond 170 bar, than steam is bypassed and sent to condenser.

Main steam isolation valve:

Close up to 40 bars, because initially pressure of steak is low, so we block the steam until its

pressure rises.

Governing valve:

On the inlet of HP turbine, these are to regulate the steam according to load demand.

Boiler master:

To watch the line and regulate the fuel and air to maintain Temperature.

If temperature is still not under control than tilting of burners

Tilting of burner:

To change the position of burner.

If still temperature is not controllable, than we inject water directly from D-Super heater, this is

the last option.

Re circulation cycle:

It is the pipe, which collect warm exhaust having unburnt particles in it, to feed again into the

furnace. This would increase efficiency. Secondly it uniformly heats the boiler when the plant is

run initially.

Fuels:

1. Diesel

2. Bunker C/ Crude oil/ Furnace oil

Usually it is very thick and cannot be pumped easily. So we warm it to 110'C and then

there are pumps which rises the pressure to 70 bars. At this temperature and pressure, it would

behave like diesel (in sense of pumping)

Temperature Pressure Ranges:

HP turbine:

Inlet 540'C 165 bars,

Outlet 320'C 35 bar

IP turbine:

Inlet 540'C 32 bars

Condenser: 0.06bar vacuum

Turning Gear: When plant is shut down

WEA13-Lec1-Gas Turbine

Kepco unit 1 and 2

Model V93.2 70MW unit Quick start unit, within minutes its on full load but its cost per unit is

higher. Its not self start, we need some media to start it.

Components:

Burning chamber Turbine Generator

Hot gases directly hit wit blades of turbine. Exhaust temperature is 500'C 70% power is used by

compressor itself, and in remaining 30% some of it is used to run auxiliary. So, the efficiency is

18%. So we install CCP(Combined cycle power plant)

To start it we install 1.induction motor, 2.Diesel engine 3.Start generator as motor

When generator start as motor, it will be synchronous motor, it has same problem of self starting,

so we gave low frequency to it, by turning gear having frequency 100rpm with the help of

Hydraulic pressure. 1.6Hz frequency.

Now slowly increase the frequency so speed of the generator(which is now working as

synchronous motor) will increase correspondingly.

Electrical circuit Control oil circuit Fuel circuit

********Electrical Circuit****** If unit is running plant supply power to the system. If unit is

shut down, power is supplied from system to the plant.

5 circuits are taken from the 6KV bus bar

1. 6Kv/540V than convert it to DC for excitation

2.Heavy oil heater 6kv/400V to heat the oil

3.Emergency circuit A small "black start generator" for emergency 4.SFC (Static Frequency

converter) circuits: It is the circuit from where frequency is regulated in order for starting. First

AC to DC, than DC to AC of our desired frequency 5.Circuit for fan and pumps

Up to 2100rpm it remains as motor.

****Lube Oil and Control oil Circuit** Air bleeding: 5th and 10 stage of the compressor 2 lines

are taken, so that from here, when plant is just started air is compressing but is not having

utilization, than Release compressed air in the exhaust so that it will not back pumped. Same is

for, when plant is shutting down.

Pilot fame: 480'C

600rpm main flame is on, but it has not enough power so that turbine can share power with the

motor.