CEB Trainig Report 1 - progress report -1

7/28/2019 CEB Trainig Report 1 - progress report -1

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INSTITUTE OF TECHNOLOGY

UNIVERSITY OF MORATUWA

REPORT ON INDUSTRIAL TRAINING

At

CEYLON ELECTRICITY BOARD

Sri Devananda RD,

Piliyandala.

NAME : K.B GONAGALA

REGISTRATION N0 : 10/IT/EE/114

COURSE : NATIONAL DIPLOMA IN TECHNOLOGY

FIELD : ELECTRICAL ENGINEERING TECHNOLOGY

PERIOD : 11 MARCH 2013 – 16 MAY 2013



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INDEX

1. CEYLON ELECTRICITY BOARD - 02

2. CENTRAL WORKSHOP - 03 – 05

3. POWER PLANT - 06 – 10

4. LIFT BRANCH - 11 – 15

5. AC BRANCH - 16 - 18



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CEYLON ELECTRICITY BOARD

The Ceylon Electricity Board (CEB), the largest electricity company in Sri Lanka. It is the major institute in charge of

electricity power in sir lanka.power generation, transmission; distribution and retailing are the major functions

coming under its authority.

CEB being its vision to enrich life through power was opened in 1969. To develop and maintain an efficient,

coordinated and economical system of electricity supply to the whole of Sri Lanka is the mission of CEB enhancing

its generating capacity to 2,684 MW, of which 846 MW is from thermal energy, and 1,357 MW is from

hydroelectricity.

Due to Low wind resource, rough terrain and poor road conditions in Sri Lanka, CEB owns only one 3 MW Wind

farm in Hambantota, known as the Hambantota Wind Farm. The farm consists of five Turbines, measuring 600 KW

each.

CEB manages numerous hydro power plants under Mahaweli and Laxapana complexes. It has ongoing main

power plant projects such as Broadlands, Trincomalee and Puttalam power plant .

Its latest projects are upper Kotmale and Lakvijaya coal power plants.



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CENTRAL WORKSHOP

In first two weeks we were assigned to be trained in Aniyakanda Central Workshop. In addition to main services carried

out by CEB it has its own workshop. For the yielding of its needs the work shop has been carried out. The

manufacturing metal accessories need for electrical repairs and installation, electrical motor repairing and automobile

repairs are carried out in the central workshop. It’s under the administration of a chief engineer, a mechanical and an

electrical engineer and mechanical and electrical superintends.

There are two main workshops. One is the electrical workshop and the other one being the metal workshop. Under

the metal workshop there is a forging workshop.

Duty of the electrical workshop is rewinding, repairing and maintaining AC and DC motors.

FAULTS AVAILABLE IN MOTORS

A/C or D/C motors may not work due to the following faults.

Damages or faults on the electricity power supply.

Damages on the electrical insulation coating on the cables such as cuts, removal of insulation coating and

bruises on it.

Thermal damages on the winding. Such as burns of burn coils.

Loose connections of the winding connections.

Wrong winding connections or terminal box.

During the time we spent in the central workshop we learnt how to carry out the rewinding of A/C motors.

Fan motor

In a fan motor there are three windings.

Stator winding

Regulator winding

Running winding

Normally the starting and the regulator winding are in the same winding. Number of turns in the regulator winding is

1/3 of the turns available in the (starting + regulator) winding.

LOW SPEED -N

MEDIUM SPPED -N

HIGH SPEED -N



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3 phase motor

In a 3 phase motor the windings must be connected such that the windings are in a balanced position. That is to

say if there are 12 windings each phase must have 4 windings.

A 3 phase motor can be power in a star and delta connected system.

Star connection delta connection

Armature winding

Armatures are used in high speed motors where higher torque is applied. Normally the speed is over 7000 rpm.

In an armature there are commutator segments as well as the slots. In some armatures the number of slots =

number of commutator segments while the other is (2*number of slots) = number of commutator segments

The coil pitch = number of slots/ poles

Number of coils per winding = number of commutator segments/ number of slots

In motor rewinding several types of insulating papers are used.

Plebian

Milliner

Luminex

Nomex

Combined paper

Letharoid

Mica



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Winding tapes are also available to tight the winding

Empire cloth

Cotton tape

Glasuoal

During three training the winding of an armature was carried out. The size of the coils was measured by a

micrometer after the coil was burnt such that the insulated coating was removed. To rewind the armature can be

carried out manually. But the process was hard and it takes a long time to rewind. Removing of the previous winding

was done using a chip. We had to care while winding the armature so that not to break the coil due to the high

tension applied on it.when such thing happed we combined two coils by soldering after the coating was removed.

In the mechanical workshop the forging process was studied.

The forging molding mixture consists of silica sand (92%) and phentonite (8%). Phentonite is used to make the

mixture strong. Cu (60-65 %) and Zn (40-35%) are used to make the brass from which the electrical accessories are

made of. The mixture is melted until it reaches 9000C. If higher strength is needed then the Zn is added 35%.the

mixture is put to the crossable cold which is made of graphite.deoxidising crystals are used to remove the air inside

the mixture to make sure no hoes are available in the final product. The cupric powder is also added to remove the

impurities in the melted mixture. If they are available they come to the surface and then they are removed.



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POWER PLANT

After that period we were trained two weeks at Power plant section – Kolonnawa. The power plant branch is

providing generator supplies where it is required. In CEB standby diesel power generator supplies for some

government institutes and various occasions they carry out maintain of the installed generators as well. Some of them are available in temple trees, presidents house, parliament and hospitals .installing the generators as well as

the maintenance is carried out by the power plant branch. Especially during the presidents meetings and during

three cricket matches CEB supplies standby diesel generators.

There we studied about large diesel power plants and its controlling system.

They own 2KW smallest generators up to 1MW huge Generators.

Type of appliance generator capacity

Homes, small shops and offices 8 to 30 kVA

Large industires,large office complexes up to 2,000 kVA

Small power plants up to about 5 MW

A 2,000 kVA set can be housed in a 40ft ISO container and fully packaged and portable. Sometimes when the

generator is larger than the engine and the generator are brought to the site and then assembled. Generators are

used not only for emergency power but also for secondary function of feeding power to utility grids either during

peak periods, or periods when there is a shortage of large power generators. Sometimes the generator supply

becomes the main supply while the CEB supply becomes secondary. Most of the time the domestic power supply

is single phase requirement while in the commercial and industrial requires it is a three phase supply.

Types of Diesel Engines

Two types of diesel engines are available

1. two-stroke

2. four-stroke

Most of the diesel engines are generally operated on the four-stroke cycle, with some larger engines operating on

the two-stroke cycle.



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Four Stroke Diesel Engines

Four-stroke cycle

Intake stroke

On the intake stroke of the piston, the piston moves from the

Top of the cylinder to the bottom of the cylinder, decreasing the pressure inside the cylinder.

A mixture of fuel (diesel) and air is forced. The intake valve then closes. Compression stroke

When the both intake and exhaust valves are closed, the piston moves upwards of the cylinder

compressing the fuel and air mixture.

Power stroke

While the piston is closed to Top Dead Center, the compressed air –fuel mixture is ignited, usually due to

the heat and pressure of compression. Large amount of energy is released and it drives the piston

upward. Due to the movement of the piston the crankshaft is rotates. The rotation of the crankshaftrotates the flywheel attached to the generator.



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EXCITOR

ROTOR

MAIN ROTOR

Exhaust stroke

During the exhaust stroke, the piston once again moves to TDC (top dead center) making the exhaust

valve is opened. The smoke due to the brunt of the fuel is released in this stroke and the other remains as

well.

Generator

R N

Y

B

There we learnt how a generator generates power... when the shaft rotates due to the rotation of the flywheel.

When the shaft rotates the main stator rotates and generates a voltage due to the rate change of flux of the main

stator. Then the generated voltage is fed to AVR and the then the regulated voltage is applied to the exciter stator.

The exciter rotary then subjected to the rate of change of flux and an ace voltage is applied. The ac supply is then

applied tom the diode plate and rectified to dc. The dc supply is applied to the rotor. But this method takes a little

time to generate the required voltage. But if we used a PMG we can generate the required voltage rapidly. R, Y and

B wires are connected to the AVR to get signal from it to check whether they are working properly.

There we learnt about the changeover. A changeover is used to change the power supply source, CEB or

GENSET. The manual change over and automatic tracking system can work as the changeover.

MAIN STATOR

MAIN STATOR

P

M

G

DIODE

PALTEE

EXCITOR STATOR

EXCITOR STATOR

AVR

SHAFT



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Generator Control Panel Features

AUTOMATIC MAINS FAILURE

ENGINE CONTROL

GENERATOR PROTECTION

3 PHASE MAIN VOLTAGE INPUTS

3 PHASE GENSET VOLTAGE INPUTS

ENGINE OIL PRESSURE MEASUREMENT

ENGINE COOLANT TEMP MEASUREMENT

BUILT IN ALARMS AND WARNING

GENSET ACTIVE POWER MEASUREMENT

GENSET POWER FACTOR MEASUREMENT

PERIODIC MAINTENANCE REQUEST INDICATOR

LED DISPLAY

There we learnt about bypass unit. A bypass unit is attached when we need to maintain or repair the ATS.

What a bypass unit does is to isolate the ATS. So we can carry out the maintains or repairs when the ATS is

attached to GENSET.

ATS BYPASS UNIT

CHANGE

OVER

BREAKER

ATS

GENERATORTO

LOAD

CEB

MAIN



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Before the generator is installed it is tested under various loads. It is done using a load bank.

LOAD BANK



11

LIFT BRANCH

Then we were assigned to the lift branch . CEB has several Lift branches in the island. A major depo is located in

General Hospital, Colombo. The function of the Lift barh is to install the new lifts and to maintain them.

There are several kinds of lifts

Passenger lifts

Dummy lifts

Home lifts

Bed lifts

PARTS OF A LIFT



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Three phas einduction motor, main sheave,auxiliary rope are called as trction machine. On the basis of the traction

machine and roping over itthere are two types of methods are available.

1:1 System 2:1 System

Since a lift is a suspended installment over several meters away from the ground necessary safety precautions

have to be taken. The aim of these safety features is to avoid and minimize the damages on passengers, goods

and the lift.

LIFT CAR

WEIGHT

=

W

COUNTER

WEIGHT

WEIGHT

= W

+

LOAD/2



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SAFETY FEATURES

Governor

Governor can detect over speed of a lift and it gives signal to motor and also mechanical break. There are two main

break system of a lift. One is electrical breaking, another is mechanical breaking. There is a maximum speed

recommended for a lift, if that speed exceeds, (If ropes Breaks, motor failures….) governor detects the problem and

car comes immediately stop. Modern lifts has an electronic sensors to detect the speed of the lift.

Limit switches (slow down switches)

Upper limit switches

Lower limit switches

These switches are used in the upper and lower limits of the hoist way. A device to slowdown and stop the

elevator at or near a terminal landing independently of the operating device. Type S3 switches are used as

slowdown switches. Normally called as 29 circuits.



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BUFFERS

Buffers are fixed at the bottom of the hoist way such that to minimize the damaged happen to the lift and the inside

resource in case of a sudden crash. There are oil buffers, hydraulic buffers are available.it absorbers the

mechanical vibrations of the defensing car or counter weight if moves beyond their limits.

Door interlocks

Land door as well as the car door is interlocked electrically and mechanically in a way that the lift doesn’t move in

case of any door being open. Modern doors are fully automatic and driven by electric motor. The door unit is again

controlled by a separate processing unit. The door mechanism is also prevented from closing the door when

passengers are entering or exiting the lift. This is done by a number of sensing devices which monitor entrance

area of the car. Also electrical interlocks prevent the lift from moving when the car door is opened.



15

CAR OPERTAING ANDFLOOR OPERATING PANEL

Car operating panel is inside the lift car while the floor operating panel is on the floor where the car is landing.

CAR OPERATING PANEL

DOOR OPERATING PANEL



16

AC BRANCH

After lift branch training we had the training in the AC branch at national hospital. The AC branch is with the

function of installing new plants, maintaining and repairing the plants.

There we studied about various types of AC plants.

Window type AC plants

Split type window AC plants

Centralized AC plants (chill plants)

Centralized AC plant

During the two weeks training I got lot knowledge on the operating of an AC plant.

Each AC plant has a compressor. Inside the compressor a refrigerant gas is filled. It may be R22, R12and R134.on

the operation of the compressor it has 4 types of compressors.

Rotary type

Piston type

Screw type

squirrel type

When the refrigerant gas is compressed by a piston or any other method out of the above it becomes hot gas. Then

the hot gas flows through the discharge tube. The discharge tube has a small diameter. Then the gas is sent to the

condenser. Fan inside the condenser makes the gas cool and it becomes a cold liquid. The cold liquid is then going

through the filter dryer that makes the liquid dry. That is due to incase of any water drops are available then they

become ice and act as barriers to the flow of the cycle. Then the liquid is the flow to the evaporator through

separate two tubes. In the evaporator the liquid absorbs the hot temperature of the room air which blows to the

evaporator by a blower. Then the cold liquid becomes hot gas and the air inside the room becomes cold and dry.

After that the cold liquid is flows through the suction pipe toward the compressor.



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There is a thermostat which helps to keep the room temperature at a constant level. When the room temperature

comes to the set temperature the gas inside the thermostat stop the function of the compressor. When the

temperature is high again it makes the compressor work. All the tube available in an AC plant is made of copper.

In a window type AC plant the compressor and the condenser are outside the room while the evaporator is insidethe room at the same position where the condenser and the compressor is fixed. In a split type AC plant the same

is inside and outside. But the compressor and the condenser can be placed several floors away from the floor

where the evaporator is placed. The centralized system the water is cooled and it is done at a point and then it is

transferred to the air handle unit. The air is intakes and it goes through bag and free filters. Then the air is releases

making contact with the tubes where the cold water flows. This is used in large scale compartments.

AC PLANT MAINTAINCE

During the training we could engaged in a practical on how to check the leaks occurs in AC plants. N2 gas is filled

to the plant in the low pressure side under 150 psi. Then the soap water is applied on the tubes to check whether

there is a leak. Then it is kept 24 hours to check whether there is a decree in the N2 pressure. If need we can check

it by sinking it in ate water. If there are no leakage then the N2 is vacuumed unit the manifold shows -30 psi. After

that the R22 gas is pressurized to the low pressure side and run the plant. When the plant runs the pressure on the

low pressure side should be 55-65 psi.

During the training of maintenance and repair of AC plants they are cleaned by water and a blower. The cap of the

evaporator is removed and then the filters inside were washed and cleaned by a blower to remove the dust

particles which makes the function of the plant weaker.



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MEASUREMENT OF PRESSURE

Measurement of pressure is done by manifold. The left side if for low pressure and the right side is for high

pressure side. The pressure is read in psi generally, while it can be read in bar also. Pressures for various

refrigerant gases are displayed on it with the temperature

CEB Trainig Report 1 - progress report -1

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