This document provides an overview of the Ceylon Electricity Board's (CEB) electricity generation capabilities. It discusses the three main types of generation used by CEB: hydro, thermal-oil, and thermal-coal. Specifically, it describes the Mahaweli hydro complex, which includes the Kotmale power station. Kotmale uses a vertical Francis turbine and has an installed capacity of 201MW, generated by three 67MW generators. The document also provides figures illustrating Kotmale's water intake and reservoir systems.

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Acknowledgements
This whole effort would not be success without the help of lot of people. Among them first I would
like to thank my family who encourage me always. Also I would like to thank the Career Guidance
Unit, University of Peradeniya to giving me this great opportunity to train in Ceylon Electricity Board.
I should thank my uncle who gave me residential facilities when I was training in Piliyandala &
Panadura. I’m so great full to all the chief engineers, electrical& mechanical engineers & electrical
superintendents who taught me a lot of stuff that I didn’t know. I should thank to all the office
members who helped me a lot and finally I should thank my friends who made this whole experience
a interesting & a joyful one.

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Contents
Acknowledgement i
Contents ii
List of figures iv
List of tables’ v
List of Abbreviations vi
Chapter 1 Introduction 1
1.1. About the training session 1
1.2. Ceylon Electricity Board (C.E.B.) 2
Chapter 2 Electricity generation in C.E.B. 4
2.1. Hydro Power Generation in C.E.B. 5
2.1.1. Mahaweli complex 5
2.1.2. Kotmale Power Station 7
2.2. Thermal- Oil Power Generation C.E.B. 12
2.2.1. Kelanithissa Combined Cycle Power Station (KCCP) 14
2.2.2. Sapugaskanda power station 16
2.3. Thermal-Coal power generation in C.E.B. 18
2.3.1. Lakvijaya (Norochchole) power station 18
Chapter 3 Electricity Transmission 21
3.1. Thulhiriya Grid Substation 22
3.1.1. Insulation Impedance testing of a transformer 22
3.1.2. Transformer relay Testing 24
Chapter 4 Electricity Distribution 25

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4.1. Distribution Division 4 25
4.2. Construction Branch Western province South I 26
4.2.1. CTPT Unit 26
4.3. Distribution Maintenance Branch (WPS I) 26
4.4. Project & Heavy Maintenance Branch 27
4.3.1. Designing of power lines 28
4.3.2. Construction of power lines 29
Conclusion 30

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List of Figures
Figure 1.1 Crest of the Ceylon Electricity Board 1
Figure 1.3 Organizational Structure of the C.E.B. 3
Figure 2.1.1. Reservoir System in Mahaweli River Basins. 6
Figure 2.1.2.1. Take structure of Kotmale power station 7
Figure 2.1.2.2. Vertical Francis turbine, Kotmale power station 8
Figure 2.1.2.3. Brushless excitation system in Kotmale Power station 9
Figure 2.1.2.4. Wicked Gates (Guide Veins) 10
Figure 2.1.2.5. Governor Operating modes 10
Figure 2.1.2.6. 1
1
2
Arrangement in Bay 1 11
Figure 2.2.1.1. Block Diagram of the Gas Turbine 13
Figure 2.2.1.2. Combustion Chambers 13
Figure 2.2.1.3 Heat Recovery Steam Generator 15
Figure 2.3.1. Electrical System of the Generator 19
Figure 3.1. Transmission network in Sri Lanka 21
Figure 3.1.1.1. Circuit Diagram for primary to earth impedance testing 23
Figure 3.1.1.1. Circuit Diagram for secondary to earth impedance testing 23
Figure 3.1.1.3. Circuit Diagram for test the impedance between primary 24
& secondary
Figure 4.1. Area controlled under DD4 25
Figure 4.2.1 CTPT unit 27

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List of Tables
Figure 1.1 Crest of the Ceylon Electricity Board
Table 1.1 Training Schedule 1
Table 2.1 Hydro Complexes in C.E.B. 6
Table 2.1.1. Hydro Power Stations in Mahaweli Complex 6

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List of Abbreviations
AFM Assistant Financial Manager
AGM Assistant General Manager
DGM Deputy General Manager
ECSC Electrical Customer Service Center
EE Electrical Engineer
ES Electrical Superintendent
FM Finance Manager
GSS Grid Substation
HP High Pressure
HT High Tension
HV High Voltage
KCCP Kelanithissa Combined Cycle Power station
LP Low Pressure
LT Low Tension
LV Low Voltage
MV Medium Voltage
PSS Primary Sub Station

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1. Introduction
1.1. About the training session
For the second session of industrial training I got the opportunity to train in Ceylon Electricity Board
again. Unlike the 1st training session in C.E.B. this time the training session was planned to cover all
three sections of C.E.B. namely generation, transmission & distribution sections. The training session
was expanded for 12 weeks from 20/10/2014 to 09/01/2015.
On the 1st day of training all the trainees were asked to report to Office of Deputy General
Manager (Training), Pliyandala & there we got our training schedule. The provided training schedule
is shown in table 1.1.
Table 1.1. Training Schedule
Branch/Workplace From To
Project & Heavy
Maintenance
Branch DD4
21/10/2014 31/10/2014
Construction Branch
WPS I 03/11/2014 07/11/2014
Distribution Maintenance
Branch WPS I 20/11/2014 14/11/2014
Transmission Operation &
Maintenance Kandy Region 17/11/2014 28/11/2014
Kelanithissa Combine Cycle
Power Plant 01/12/2014 05/12/2014
Sapugaskanda
Power Station 08/12/2014 12/12/2014
Lakvijaya Coal
Power Station 15/12/2014 26/12/2014
Kothmale Hydro
Power Station 29/12/2014 07/01/2015

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1.2. Ceylon Electricity Board (C.E.B.)
Figure 1.1 Crest of the Ceylon Electricity Board
 Vision
Enrich Life through Power
 Mission
To develop and maintain an efficient, coordinated and economical system of electricity supply to the
whole of Sri Lanka, while adhering to its core values: Quality, Service to the nation, Efficiency and
effectiveness, Commitment, Safety, Professionalism, Sustainability.
Ceylon Electricity Board (also abbreviated C.E.B.) is the largest electricity company which controls
all aspects of electricity namely generation, transmission & distribution in Sri Lanka. C.E.B.
generates 74% [1] of the total demand while it controls the whole transmission process. Other than
the small area that Lanka Electricity Company (LECO) involves in electricity distribution, electricity
distribution in all other areas is controlled by C.E.B.
The history of C.E.B. begins with the Aberdeen-Lakshapana hydro electricity
proposal in 1924 which leaded to the establishment of ‘Electricity Department in 1926. Then it
changed as ‘Electricity Board of Ceylon’ in 1936 & finally as ‘Ceylon Electricity Board’ on 1st
November 1969.

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1.2.2 Organizational Structure of the CEB
Figure 1.3 Organizational Structure of the CEB

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2. Electricity Generation in C.E.B
C.E.B. generates typically 74% of the total electricity demand of Sri Lanka. C.E.B. purchase electricity
from P.P.P. (Private Power Purchases) to fulfil the remaining electricity demand. Electricity generation
in Sri Lanka can be categorized into 4 major categories. They are
• Hydro
• Thermal-oil
• Thermal-coal
• NCRE
Contribution of each category depends on several facts like weather (rain), fuel prize, condition of
plants etc. For an example consider following charts taken from the ‘Statistical Digest of the C.E.B.
2013’.
By considering above carts it can be seen that rainfall in 2012 is less than 2013. That’s why Hydro
electricity generation in 2012 is less than 2013. As well in 2013 only the phase 1 of Lakvijaya
(Norochchle) coal power plant was operational. That’s why contribution from thermal-coal power
plants is less than the contribution from thermal-oil power plants.

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2.1. Hydro Power Generation in C.E.B.
Hydro power plants owned by C.E.B. can be categorized into 3 complexes. They are given in the
table 2.1.
Table 2.1 Hydro Complexes in C.E.B.
Complex Capacity (MW)
Mahaweli Complex 335
Laxapana Complex 816
Samanala Complex 214
In our training program in C.E.B. we were allowed to choose one of these complexes as our training
place. So I & my group chose Mahaweli complex.
2.1.1. Mahaweli Complex
Mahaweli complex is the hydro complex that has the highest capacity of all three hydro complexes.
It has 8 hydro power stations which are given in table 2.1.1.
Table 2.1.1. Hydro Power Stations in Mahaweli Complex
Power Station Installed Capacity
Victoria 210
Kotmale 201
Randenigala 122
Rantambe 50
Ukuwela 40
Bowathenna 40
Nilambe 3
Upper Kotmale 150

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Mahaweli complex hydropower system consists of Thalawakele, Kotmale, Victoria, Polgolla,
Randenigala & Rantambe reservoirs. Figure 2.1.1 shows the reservoir system in Mahaweli river
basins.
Figure 2.1.1. Reservoir System in Mahaweli River Basins.
On the 1st
date we went to the head office of Mahaweli Complex in Kandy. There we were again
separated into two groups and one group was assigned to Upper Kotmale power station while the
other group was assigned to Kotmale power station. I was assigned to Kotmale power station.

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2.1.2. Kotmale Power Station
Kotmale power station is the 2nd
largest hydro power station in Sri Lanka with an installed capacity
of 201MW. It was opened in April 1985 with one 67MW generator & the 2nd
& 3rd
generators were
installed February 1988 & February 1989 respectively with the financial assistance by the government
of Sweden. It is based on the reservoir on the Kotmale oya formed by Kotmale dam.
• Kotmale Dam & Reservoir
Kotmale dam is a concrete membrane rock fill dam with a maximum height 87m above the bed level.
It blocks Kotmale ova and forms the Kotmale reservoir with
Top water level (TWL) 703m – MSL
Maximum flood level 704.3m -MSL
Minimum operation level (MOL) 665m - MSL
Gross storage up to TWL 174 x 106
m3
• Take Structure
Take structure of the Kotmale power plant can be represented as in figure 2.1.2.1

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Figure 2.1.2.1. Take structure of Kotmale power station
 Low pressure tunnel is totally 6954m long with a maximum capacity of 113.3m3
/sec &
creates a 65.2m head
 High pressure tunnel (Penstock) is 120m long & it creates a 105.9m head
 Surge Shaft (Tank)
Surge tank is there to critically damp the water flow when a sudden rise of pressure (When
the Main inlet valve is closed suddenly)
• Turbine
It can be seen 3 types of turbines in hydro plants in Sri Lanka. They are
 Pelton - For large head
 Francis - For medium head
 Kaplan - For low head
As Kotmale plant has a head of 193m head w.r.t. to the minimum operation level, in Kotmale power
station we can see vertical Francis Turbines which are designed for 201.5m head.
▽ 584.7m
▽ 478.8m
▽ 649.9
▽ 765.5m

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Figure 2.1.2.2. Vertical Francis turbine, Kotmale power station
• Generator
Kotmale power station contains three 67MW generators. All three generators are 16 poles machines
& the speed of rotation is 375rpm. Generation voltage of these machines are 13.8kV and then it is
stepped up to 220kV in the switch yard.
Usually it is capable to use brush exciters as the rotation speed is low. But in Kotmale power
station, even though exciters used initially were brush exciters they have been replaced by brushless
exciters due to accumulation the dust released by brush exciters which made the maintenance is harder
& expensive. Brushless exciters in Kotmale power station has 20 poles in each & they can be powered
up by either generator itself , by the power in national grid or by the battery bank which is used only
in a total blackout.
In my training period in Kotmale power station I got the rare chance to see a maintenance in
unit 3. There I got the chance to see the inside of the brushless exciter system which is shown in
figure 2.1.2.3
Figure 2.1.2.3. Brushless excitation system in Kotmale Power station

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• AVR System
AVR determined the dc current and voltage that should be supplied to achieve the required output
voltage. This was controlled by varying the firing angle of the thyristor bank depending on the
terminal voltage and output current of the generator. Before synchronizing, AVR is responsible to
build up the terminal voltage appropriate to the system voltage. After synchronizing, AVR is
responsible to control the reactive power output of the generator by changing the excitation.
• Governor
Frequency control of the generator is done by the governor. By controlling the frequency it means to
keep the generator frequency matched to the system frequency with the varying load. For that in a
hydro power plant the governing action is to control the wicked gates. In Kotmale power station, an
electro hydraulic actuator is used to control 24 wicket gates by applying 40 bar hydraulic pressure.
Figure 2.1.2.4 shows the wicked gates of a machine in Kotmale Power station.
Figure 2.1.2.4. Wicked Gates (Guide Veins)
Before synchronizing governor is used to speed up the machine up to 375rpm & after synchronizing
it is used keep the frequency matched to the system frequency with the varying load. So in these two
situations governor works in two different modes. In the power station they are called ep1 mode &
ep2 mode where
 ep1 - Frequency control mode
 ep2 - Power control mode

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f
P
ep2
ep1
With ep1 mode it allows to achieve a large change in the frequency while change in the power is
small.ep2 mode allows to control power while change in the frequency is small w.r.t. change in the
power as shown in figure 2.1.2.5
Figure 2.1.2.5. Governor Operating modes
• 220 kV Switch Yard
The specialty I saw in the Kotmale switch yard was instead of 3ph transformers there it had been used
three separated single phase transformers. So in the whole yard there were 9 single phase
transformers. All together it could be seen 8 feeders namely
 Anuradhapura 1 &2
 Upper Kotmale 1 & 2
 Victoria 1 & 2
 Biyagama 1 & 2
Feeder arrangement in Kotmale power station 220 kV switch yard was also an interesting one. It is
called the 1
1
2
arrangement which is shown in figure 2.1.2.6

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In this method a bay is containing 3 breakers, so the two bus bars are owning 3 breakers. So 1
1
2
breakers to a bus. That’s how its name come from. This arrangement is there for redundancy purposes.
With this method it allows to energize Anuradhapura line through bus bar 1, bus bar 2, or directly
through Victoria 1 line.
2.2. Thermal- Oil Power Generation C.E.B.
Before Lakvijaya coal power plant come into the picture the two main thermal-oil plants namely
• Sapugaskanda power station
• Kelanithissa combined cycle power station
had a huge impact on electricity generation in Sri Lanka. But now they are only used if it is essential
to use them as they carries a higher per unit cost.
In our two weeks of training in the Thermal-oil power plants, on the 1st
day we had to report to D.G.M.
thermal complex and there we were assigned to Kelanithissa power station & Sapugaskanda Power
station for a one week training in each of them
Anuradhapura 1
Victoria 1
Figure 2.1.2.6. 1
1
2
Arrangement in Bay 1

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2.2.1. Kelanithissa Combined Cycle Power Station (KCCP)
Kelanithissa combined cycle power station has total capacity of 165MW contributed by 110MW from
the gas turbine & 55MW from the steam turbine. KCCP has the ability to work as an open cycle plant
as well as a combined cycle plant.
• Gas Turbine
For the gas turbine both naphtha & diesel can be used for the combustion. Out of two naphtha is
cheaper and also highly flammable than diesel. So naphtha is used frequently than diesel. As well as
KCCP is the only power station that uses naphtha. Otherwise naphtha from oil refinery will be remain
as a waste. So using naphtha is good for the environment too. Diesel is only used in starting & shut
down of the plant when the generation output is less than 40MW. Both fuels have separated filtering
skids & there is a separate super lubricant injection skid to mix super lubricant with naphtha as it has
a low viscosity. Block diagram of the gas turbine is given in figure 2.2.1.1.
• Combustion Chamber
Turning
Gear
Cranking
Motor
Torque
Converter
Gear
Box
Bearing
Inlet Guide
Vent (IGV)
Compressor
17 stages
Combustion
Chamber
Bearing
Turbine
3 stages
Bearings
Bearing
Exciter
Generator
Figure 2.2.1.1. Block Diagram of the Gas Turbine

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Filtered air taken from outside through inlet guide vent (IGV). Then the mixture compressed up to 10
bars by 17 stage compressor and supplies to the combustion chamber which is shown in the figure
2.2.1.2.
Combustion chamber includes 14 separate chambers and each combustion
chamber is supplied with atomizing air, fuel at 37.5 bar and compressed air. In order to obtain a
proper combustion, atomizing air was necessary. Ignition is done only in 13th and 14th chambers.
Then the fire spreads to the other chambers through cross fire tubes. To identify the condition and
spreading of the ignition, flame detectors had been included in the 4, 5, 9 and 11 chambers.
Figure 2.2.1.2. Combustion Chambers
The combusted air is directed towards the turbine chamber via nozzles and buckets. Shaft of the turbine
is coupled with a 2 pole generator. So the shaft has to rotate at a 3000rpm speeds to keep 50Hz frequency.
Like water flow in the hydro power generation in KCCP, governor of the gas turbine controls the fuel
flow to the gas turbine to control the frequency w.r.t. varying load. Generating voltage and the capacity
of the generator is kV and 115MW respectively. 15kV generated voltage is brought to the step up
transformer via SF6 breakers and step up to 220kV for transmission.
Combusted air after the gas turbine can be exhausted through the chimney or it can be directed to boil
the water and make the steam. The direction is done by the damper.
• Steam Turbine

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The combusted gas after the gas turbine is at a temperature about 5600
C. This is directed towards the
heat recovery steam generator (HRSG) to generate the steam. HRSG generates the steam in two
different pressure levels.
 Low pressure steam
 High pressure steam
From the feeding water pumps, water is discharged to the HSRG at two pressures as LP discharge
and HP discharge. LP discharge line carried water to the LP economizer, where heating of water is
done. Both generated steam and water was collected to the LP drum where the separation of dry steam
is carried out. In order to maintain the temperature inside the drum, water is circulated through LP
evaporator by using circulation pumps. Collected steam at the LP drum was then directed to the super
heater in order to super heat the steam. Resulted steam is directed to the LP turbine. Other than having
two economizer stages for HP steam to bring them to a very high temperature, same process is carried
out for HP discharge water. At the end of the process, high pressure steam with pressure of 65-70
bars and with temperature of 511 0C was produced. These produced steam was brought to the HP
turbine. HP steam was passed through a stop valve, which was used to control the flow of steam to
the turbine. Then the governor was came into action. It controlled the steam amount that should be
supplied to the turbine depending on the power demand.
HP steam rotates the HP turbine at speed of 9400 rpm and it is reduces through a gear box up to
3000rpm & then coupled to the generator. Exhaust steam from the HP turbine as well as the LP steam
directed to the LP turbine & it rotates at a speed of 3000rpm. It also coupled to the generator by the
same shaft. The generator is capable of generating output power of 55MW. The whole process is
given in the figure 2.2.1.3.

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2.2.2. Sapugaskanda power station
Exhaust Gas From
GT (5600
C)
Cooling water
2X Feed Water
Pumps
HP (100 bar)
LP (30 bar)
LP
Drum
HP
Drum
Circulating pump
Circulating pump
Governor
HP
Turbine
LP
Turbine
Gear
Box
Exciter Generator
55MW
Condenser
Condensate
excitation pump
Gland steam
Condenser
Pre- Heater
Detractor
Feed water tank
LP economizer
HP economizer
LP evaporator
HP evaporator
HP super heater
Figure 2.2.1.3 Heat Recovery Steam Generator

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Sapugaskanda power station has an installed capacity of 160 MW with the contribution of 4x20 MW
generators in station A ( built in 1984) & 8x10 MW generators in section B ( built in 1998). All of these
generators are driven by 4 stroke engines. Only at the starting & shut down engines are driven by diesel.
Otherwise they are driven by heavy fuel. Generating voltage in all machines is 11kv. Then it is stepped
up to 132 kV & transmitted to Biyagama.
• Generator starting process
During my training period in Sapugaskanda power station I was able to see the starting process of a
generator. The procedure was like below.
 Turning gear (an electrical motor connected to crank shaft) is turned on to remove stocked
water vapor inside the engine.( speed of the motor is about 0.5rpm & the crank shaft was
turned about 2 rounds)
 Then the speed is increased up to 70rpm by ‘starting air’ (pressured to 30bars)
 Then the engine is begun to run from diesel & the speed is up to 200rpm & kept at 200rpm
for 5 minutes for check conditions of auxiliary systems
 When the necessary conditions are reached
o Governor should be loaded more than 30% of the full load
o Temperature of the engine cooling water (jacking water) > 700
C
o Temperature of heavy fuel > 900
C
engine fuel is changed from diesel to heavy fuel
 When the speed of the engine passed 385rpm, control panel of the generator in the control
room indicates that generator is ‘ready to excitation & synchronization.
 When the speed of the engine reached 410rpm control room takes the control of speed.
 After that field breaker switch closed & excitation is done
 Then synchronizing process begins. When the synchronization is done following conditions
should be considered
o Voltage level of the system & generator should be equal
o Frequency of the generated voltage & frequency of the system
should be equal
o Phase sequence of the generator & the system should be
matched (done when the commissioning is done)

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o Both generated voltage & the system voltage should be in phase
(in Sapugaskanda power station dark light method is used)
 All of these conditions should be matched at the synchronizing moment
 After synchronizing is done loading is begun.
o Synchronization is done , keeping the load setting at 2 MW to
avoid the reverse flow
 Then the load is gradually increased according to temperature of the cylinders
o Normally 1 MW per minute
• Arrangements made to improve the efficiency of the power station
 Turbo charger
Turbo charger is a compressor which is connected to a turbine operated by the exhaust air from the
engine. This produces the charged air to the engine
 Hot water system
As the viscosity of the heavy fuel is high it has to heat the fuel to reduce the viscosity. This is done
by using hot water. To increase the efficiency of the power station it has used hot air exhaust from
the engine to heat the water.

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2.3. Thermal-Coal power generation in C.E.B.
Thermal-coal power generation is a new trend that power generation in Sri Lanka achieved reason
past. At the moment Lakvijaya power station is the only coal power station in Sri Lanka. There is
Sampur coal power station which is under construction still. Per unit cost in a coal power station is
so much less than per unit cost of a thermal-oil power plant. So in Sri Lanka for last two three years
thermal-coal power generation has contributed more than thermal-oil power generation to fulfil the
electricity demand of Sri Lanka.
2.3.1. Lakvijaya (Norochchole) power station
Initial feasibility studies for Lakvijaya power station was started in 1996 & the contact was signed
with the government of China on 15th
March 2006. The project consisted of three stages (3x300 MW).
In the 1st
stage it was supposed to cover phase 1 of the power station with 300 MW & phase 2 of the
power station consists of 2x300 MW units was supposed to be covered in the 2nd
stage. At the time I
was there commissioning of the unit 3 was also finished & the plant was able to generate 900 MW.
Usually for a thermal oil plant the unit cost is around Rs.24/- where in Lakvijaya power station the
unit price is about Rs.8/-. So it is clear that it saves a huge amount of money to the Sri Lanka
government.
• Turbine & the generator
As mentioned earlier, Lakvijaya power station consists of three 300MW with an apparent of
353MVA. The generation voltage of the generators is 20 kV. All the generators are 2 pole generators,
so to achieve 50Hz frequency the rotor of the generator should be rotted at a speed of 3000rpm. For
that steam generators are used. When compared with generators found in other plants, I was able to
identify certain specific features in the generators used in Lakvijaya Power Station. They are,
• They are consisted of a cooling system operated with water and hydrogen.

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• Generator chambers are filled with hydrogen and it acted as a cooling medium. By maintaining
a thing oil layer in the either sides of the generator, leakage of the gas had been prevented. It
also prevent the entry of dust to the generator chamber.
• It was consisted of stator cooling system, in which water flows with stator coil. Short circuiting
caused by the water had been prevented by using deionized water with less conductivity.
Each generator is driven by a HP turbine, IP turbine & two LP turbines. Steam exhausted from the
HP turbine is reheated & then supplied to the intermediate pressure turbine then the steam is directly
supplied to two LP turbines.
 Main steam pressure – 16.7 MPa
 Main steam Temperature – 5380
C
 HP turbines -1 control stage + 12 stages
 IP turbines – 9 stages
 LP turbines -7 stages
• Excitation system
In Lakvijaya power station generators are excited by using brushes & sliprings method. Here dc
voltage for excitation is produced by stepping down & converting the output voltage of the generator.
Electrical system of the generator can be represented as in figure 2.3.1
• FDR
G
20 kV
220 kV bus bar
For transmission
A
UAT (for auxiliary systems)
B
Thyristor bank
X
X
AVR
PT
panel
Field Breaker
FDR
Brushes
Rotor
Figure 2.3.1. Electrical System of the Generator

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When the field breaker is opened, there will be a back emf induced in the rotor windings. So
the field discharge resistor (FDR) is there to dissipate the power generated by that emf
• AVR
Auto voltage regulator (AVR) takes the voltage reading from the PT panel & compares it with
the set voltage. Then it controls the firing angle of the thyristors to correct the excitation to
generate the set voltage.
• Boiler
 Maximum continuous rate - 1025 tons/hrs.
 Main steam pressure - 17.3 MPa
 Main steam temperature - 5410
C
Boilers in Lakvijaya power station are called balanced draft boilers. It means that both intake &
exhaust air rates are equal. Intake air to the furnace is controlled by forced draft (FD) fans (x2) &
induced draft (ID) fans are there to pull out the flue gas.
Boiler controlling is done with the aid of a PID controller. Here boiler controlling is done in two
ways. When the generated power is less than 100 MW single element method is used where only dru
level is taken. When the generated power is higher than 100 MW three element method is used where
drum level, steam flow rate & water flow rate are taken in to account.
• Run Back Process
In case of where it has to dead the system very quickly run back process is activated. When it is
activated
 One of the FD fan & the ID fan against are stopped
 In case of stopping a primary fan the load has to be reduced to 150MW. For that it stops the
coal supply by 3mills & reduce the fuel supply, at that time only 4 oil guns in the dc layer is
activated.

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3. Electricity Transmission
Though C.E.B. does not generates the total electricity demand of Sri Lanka it in electricity
transmission C.E.B. own the total transmission network in Sri Lanka. In C.E.B. it can be recognized
two transmission voltages, 132 kV & 220 kV. Figure 3.1 shows the transmission network in Sri Lanka
in 2014.

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Figure 3.1. Transmission network in Sri Lanka
In our training in C.E.B. we were allowed to choose one of transmission region from the three of
 Kandy region
 Anuradhapura region
 Colombo Region
Among them I chose Kandy Region. During the two weeks of training in the transmission, Kandy
region branch, on 1st
date I had to report to the head office in Asgiriya. There I was assigned to
Thulhiriya grid substation.

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3.1. Thulhiriya Grid Substation
Thulhiriya grid substation is one of the major GSSs owned by, transmission operation & maintenance
branch Kandy region. It consists of three 31.5 MVA transformers. Polpitiya- Athurugiriya 132kV
double circuit line is tapped in Raththota and then it has been fed to the Thulhiriya GSS. There it is
stepped down to 33 kV fed to 11 output feeders from the grid.
During the time I was been there, a routine maintenance was carried out. In a routine
maintenance they check each & every transformer to see, whether they are in good condition,
wheatear the transformer protection alarms & relays works well, etc. so I got the chance to learn a lot
of stuff there.
3.1.1. Insulation Impedance testing of a transformer
Insulation impedance testing is done basically for three sections. They are
 Primary winding to earth insulation impedance
 Secondary winding to earth insulation impedance
 Insulation impedance between primary & secondary
• Primary to earth insulation impedance testing
In Thulhiriya GSS there are star/delta transformers. So when it is to test primary to earth insulation
impedance, 1st
of all the neutral earth of the star connection is disconnected & the secondary side is
earthed. Then all three phases & the neutral is short circuited & circuit is connected as in figure
3.1.1.1.
Megger
Impedance which is
tested

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Figure 3.1.1.1. Circuit Diagram for primary to earth impedance testing
• Secondary to earth insulation ipedence testing
Here also primaryside is earthed & then all three phases of secondary side are short circuted a the
circuit diagram is given in the figure 3.1.1.2.
Figure 3.1.1.1. Circuit Diagram for secondary to earth impedance testing
• Insulation impedance between primary & secondary winding
Neutral earth of the primary side is disconnected & the circuit is connected as is figure 3.1.1.3.
Megger
Impedance which is
tested
Megger
Impedance which is tested

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Figure 3.1.1.3. Circuit Diagram for test the impedance between primary & secondary
If there aren’t any insulation faults results of all above tests should be in GΩ range. After testing is
done for the main transformer all three test were the auxiliary transformer as well.
3.1.2. Transformer relay Testing
Transformer protection system has sensors which are connected to relays which are operated when
sensors felt a fault. In relay testing these relays are manually operated by creating fault conditions.
• Transformer temperature sensor testing
There’re three kinds of temperature sensors inside the main transformer. They are
 HV winding temperature sensor
 LV winding temperature sensor
 Oil temperature sensor
When testing, these sensors are taken out and then immersed in a separate oil container. Then the oil
inside the container is heated up to see weather
 Cooling fans are turned on
 Alarm indications are come
 Tripping is done
at the temperatures which they have been set.

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4. Electricity Distribution
Other than the small area that LECO distributes the electricity, electricity distribution in all other
areas done by C.E.B. C.E.B. has divided these areas to four distribution divisions based on the
revenue. As I was in DD2 during my last training session, this time I chose DD4.
4.1. Distribution Division 4
DD4 is again sub categorized into two provinces controlled by D.G.M.s they are
 Western province south I
 Sothern province
Area controlled under DD4 is the area that is darken in the Sri Lanka map in figure 4.1
Figure 4.1. Area controlled under DD4

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4.2. Construction Branch Western province South I
All the LV line constructions & part of the MV line construction works are done by the construction
branch. Apart from that distribution substation installation is also don by the construction branch.
Apart from the stuff I learned from my last training in the construction branch of central province
the new experience that I got is, I had the chance to visit the construction site of Army Hospital in
Werahera. There I got the rare chance to see a CTPT unit installation.
4.2.1. CTPT Unit
When the HT metering is done it has to use a CTPT unit. CTPT unit uses the 2 wattmeter method to
measure the power. The CTPT unit is given in figure 4.2.1
Figure 4.2.1 CTPT unit

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4.3. Distribution Maintenance Branch (WPS I)
Distribution maintenance is the provincial body which is responsible for maintaining of pole lines,
distribution or bulk substations in the province. Addition to that, repairing of tools, conducting cost
paid jobs like pole shifting, transformer shifting, conducting system augmentation works and
inspecting substations in the area are some other services given by this branch.
During my training time in the distribution maintenance branch (WPS I) I could see all kind of
materials used in LV & MV line constructions. As well as I got the chance to visit
 A new pole line construction site in Welipanna
 Pole removal job in Dampe area
 A routine maintenance in Fulton
Not only the maintenance jobs but also inspections future proposals are done by the Distribution
maintenance branch. In my training time there I could attended to inspections on future proposals in
Ratmalana & Mt.Lavinia.
During my training period in distribution Maintenance Branch (WPS I) I could see three different
types of distribution transformers. They are
 Single pole mounted - 100 kVA/ 160kVA
 Double pole mounted - 250 kVA / 400 kVA
 Plinth / Cubical mounted - 630 kVA /1 MVA

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4.4. Project & Heavy Maintenance Branch
Unlike construction or distribution maintenance branches there is only one Project & Heavy maintenance
(PDM) branch in a distribution division. PDM branch takes care of
 33 kV MV line construction & maintenance (tower lines)
 Primary Substation construction & maintenance
 Hot line maintenance
in the distribution division
4.3.1. Designing of power lines
I had the chance to visit tower line constructions sites. Atakohota and Thissamaharama areas, where
line construction processes were carried out. As I understood, there were mainly four steps followed in
line designing.
1. Basic design of the line
When the starting and ending points of a line are given, first conductor line is drown over a
1:50,000 map or in a Google map in the shortest possible way considering natural and artificial
obstacles in the path.
2. Preliminary Survey
A survey is conducted collecting details over a strip of 60m wide to the either sides of the proposed
line. Most of unseen obstacles are identified in this process. Depending on the obstacles, necessary
changes are done to the proposal. It may contain straight line paths, angle points with Medium
angles (0-30) and Heavy angles (30 - 60), terminal ends etc.
3. Profile Survey
Under profile survey collecting of details of the selected route is done. Elevated profile of the
region of 20m width along the selected route is taken. In this levels environmental facts and laws
and regulations should be considered.
4. Line designing
Tower type, foundation type, height, construction procedure is decided under line designing.
During line designing, conductors are drown in their real shape (Centenary shape) using software

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like AutoCad or using templates. In line designing much attention is drown to the maintaining of
“Sag Tension”. To maintain the sag tension, features like basic span, wind span, weight span are
considered.
4.3.2. Construction of power lines
In power line construction, suitable tower type should be selected considering facts like span, angle,
number of circuits, required height, terrain and etc. I was able to identify basically two types of towers
as,
• Tower type : used with height of 13m and span of nearly 400m
• Mast type : used with height of 11m and span of nearly 200m
Depending on the specifications of the towers, a logical name system was used for the easiness of
identification.
Ex : TSM – Tower type, Single circuit, Medium angle
MSM – Mast type, Double circuit, Medium angle
After the identification of the required tower types, construction of the line was carried out in the
following order.
• Laying of foundation.
• Erecting towers
• Stringing
• Commissioning.
I was able to observe a working site at Elpitiya, where stringing was done. Part of a line in between two
angle points was considered as a single “Section”. Stringing can be started from any of such section. To
keep the wires tensioned while stringing was done, stray wires or guy wires were used. First a rope called
“Pilot” was send from tower to tower over pulleys. Then the conductor was attached to the rope using a
special equipment. Stretching and tensioning of the conductor was done by using special equipment
called “Tensioner” and winding machine.
At each angle point and by every 8 piles, a jumper point is added. It is useful when it is necessary to
isolate the certain part of a line from the rest. Mainly two types of insulators as, suspension and tension
type were used to hang the conductors. Addition to that vibration dampers were added to prevent the
unnecessary swing of power lines.

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Conclusion
My second training session of 12 weeks with the Ceylon Electricity Board do teach me lots about the
working experiences and its challenges as an Engineer. CEB was a good platform for me to practice
both technical and non-technical knowledge skills in real life applications. Furthermore, this
experience opened my eyes to see the link between engineering theories we learn with the real world.
It also helped me to improve my soft and functional and communication skills too.
My internship training as an undergraduate was a great opportunity to observe, identify and practice
how engineering is applicable in the power sector. I was able to gather much knowledge on power
generation, transmission and distribution and also about the new upcoming technological trends in
power engineering. It was not only to get experience on technical practices but also to observe
management practices and to interact with fellow workers. I was able to get an understanding about
the structure of an organization and cascading of responsibilities within the organization. All these
valuable knowledge and experience that I have gained were not only acquired through work
observation but also through the direct involvement and through the other aspects of the training such
as interaction with the superior and other people related with the field, through manuals and annual
publication reports etc.
During my training, I understood the impotency of exposure given by the academic program in fields
like Electrical, Electronic, Controlling, Networking and Programming, which were useful in
understanding the real world engineering applications. It was a bridge to fill the gap between the
engineering theories and engineering applications.
Switching between several training locations rather than staying in a single place was lot more useful
and also was a great experience in my life. It helped me to cover larger area in power sector and was
a great experience which taught me the impotency of punctuality, maximum commitment and the
team spirit.

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From what I have undergone, I am pretty sure that industrial training program has achieved its primary
objective. As the result of the program I am now more confident and aware in fulfilling my necessities
which are needed for the path of success as a professional.