Industrial Training Report

UNIVERSITY OF MORATUWA

Faculty of Engineering

Non-GPA Module 399: Industrial Training

INDUSTRIAL TRAINING REPORT

Kularathna M.P.D.S.C.Registration No: 080246F

Department of Electrical Engineering

Lanka Electricity Company (Pvt) Ltd

Ceylon Electricity Board

Amithi Power Consultants (Pvt) Ltd

From 02nd of March 2011 to 03th of September 2011

Date of submission - 17th of September 2011

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PREFACE

This report was prepared as a requirement at the end of our Industrial Training period.

This training was a great opportunity to expose ourselves to industrial environment, let us to apply the

knowledge we gathered at the university and to gain some experience about the industry.

I have included my experiences, skills and practices I gained for 24 weeks duration starting

from 28th February 2011 to 12th August 2011 about electrical engineering field as an electrical

engineering undergraduate trainee of the University of Moratuwa at Ceylon Electricity Board, Lanka

Electricity Company (Pvt) Ltd and Amithi Power Consultants (Pvt) Ltd.

The report consists of 3 major chapters. First chapter mainly includes Information about

Training Establishment. This Chapter begins with a brief introduction of each training places .Then

First chapter describes main functions, Organizational Structure and hierarchical levels, Present

Performance, Strengths, Weaknesses, profitability, Usefulness to Sri Lankan Society of each training

Establishments.

The second chapter describes daily entries in detail, it contains about the technical experience

and knowledge which I have gathered during my training period, in different places in CEB and

LECO. Also in there I have included many electrical designs involved in APCL and gathered

knowledge and experiences while involved in those designs.

The third or final chapter includes the conclusion of the report. This conclusion include an

assessment on the current Industrial Program which coordinated by University Of Moratuwa. There

have summarized training experienced which I gained for 24 weeks within Ceylon Electricity Board,

Lanka Electricity Company (Pvt) Ltd and Amithi Power Consultants (Pvt) Ltd. I added my comments

that describe how Industrial Training should change to provide a maximum merit to implant trainees.

Also I appended comments and suggestions that describe how industrial training program should

improve.

Kularathna, M.P.D.S.C.

Department of Electrical Engineering

Kularat hnaM . P .D .S .C .ii

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University of Moratuwa

ACKNOWLEDGEMENT

Here my sincerely thanks go to the Industrial Training Division of University of

Moratuwa and National Apprentice & Industrial Training Authority (NAITA) for taking all the

necessary arrangements for making this training program a success and giving me this opportunity

to gain the in plant traineeships in Ceylon Electricity Board, Lanka Electricity Company (Pvt) Ltd and

Amithi Power Consultants (Pvt) Ltd.

I would like to express my gratitude towards all the Engineers, technicians, workers and other

staff of Ceylon Electricity Board in Samanalawewa Power Station, Sapugaskanda Thermal Plant,

Kelanithissa Power Plant, Kelanithissa Combined Cycle Power Plant, Generation & transmission

Planning division, Transmission Operation and Maintenance (Colombo region), System Control

Centre, Rathmalana GSS and Pannipitiya GSS for spending their valuable time and sharing their

knowledge to success my in plant traineeship.

Next I should convey my gratitude for who helped me in Lanka Electricity Company (Pvt) Ltd,

all the Engineers, technicians, workers and other staff of Maharagama Customer Service Centre,

Branch Office, Operation Division, Engineering Division and Ekala-Training Centre for enhancing my

knowledge about electrical engineering field and receiving necessary experiences and skills.

Next my special gratitude go to Mr. D.G Rienzi Fernando, Chairman and Managing Director

of Amithi Power Consultant (Pvt) Ltd for his decision to recruit engineering students as trainees and

support he gave in various ways to develop our practical knowledge and I would like to thank the

entire staff of the Amithi Power Consultant (Pvt) Ltd.

It’s very important to memorize and give my special gratitude my parents, my friends, and

especially my dear Mrs Suwanthri Katuwapitiya, be with me and help me in various ways to complete

my training report successfully.

Kularat hnaM . P .D .S .C .iii

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Kularat hnaM . P .D .S .C .iv

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Table of Contents

1. Introduction to the Training Establishment..........................................................................................1

1.1 Lanka Electricity Company (Pvt) Ltd......................................................................................1

1.1.1 Introduction to LECO...............................................................................................................1

1.1.2 History of the LECO................................................................................................................1

1.1.3 Vision and Mission of LECO...................................................................................................2

1.1.4 Organization Structure of the LECO........................................................................................2

1.1.5 Present Performances and Strength of the LECO....................................................................2

1.1.6 Profitability of the LECO.........................................................................................................2

1.1.6 Usefulness of LECO to Sri Lankan Society.............................................................................3

1.2 Ceylon Electricity Board.................................................................................................................3

1.2.1 Introduction to CEB.................................................................................................................3

1.1.2 Organization Structure of the CEB..........................................................................................4

1.2.3 Present Performances and Strength of the CEB.......................................................................4

1.2.4 Usefulness of CEB to Sri Lankan Society...............................................................................4

1.2.4 Suggestions for improvements.................................................................................................4

1.3 Amithi Power Consultants (Pvt) Ltd...............................................................................................5

1.3.1 Introduction to APCL...............................................................................................................5

1.3.2 History of the APCL................................................................................................................5

1.3.3 Organization Structure of the APCL........................................................................................5

1.3.4 Present Performances and Strength of the APCL....................................................................6

1.3.5 Profitability of the APCL.........................................................................................................6

1.3.6 Suggestions for improvements.................................................................................................6

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1.3.7 Usefulness of APCL to Sri Lankan Society.............................................................................6

2. TRAINING EXPERIENCES...............................................................................................................7

2.1 Training Experience in Lanka Electricity Company (Pvt) Ltd.................................................7

2.1.1 Maharagama LECO Depot.......................................................................................................7

2.1.1.1 HT maintenance................................................................................................................7

2.1.1.2 Consumer Breakdown maintains......................................................................................8

2.1.1.3 Field billing.......................................................................................................................8

2.1.1.4 Disconnecting process......................................................................................................8

2.1.1.5 Breakdown registry...........................................................................................................8

2.1.1.6 Equipments and Materials use in LECO Depots..............................................................9

2.1.2 Nugegoda LECO Branch Office........................................................................................10

2.1.2.1 LECO Construction work...............................................................................................10

2.1.2.2 Planning & construction.................................................................................................11

2.1.2.3 Job Costing.....................................................................................................................11

2.1.2.4 LV Planning....................................................................................................................12

2.1.3 LECO Head Office.................................................................................................................12

2.1.3.1 Engineering Division......................................................................................................12

2.1.3.2 Load forecast..................................................................................................................12

2.1.3.3 Planning..........................................................................................................................12

2.1.3.4 Load flow analysis..........................................................................................................11

2.1.4Operation Division.............................................................................................................11

2.1.4.1Distribution Control Centre.............................................................................................11

2.1.4.1.1 Task of system control centre..................................................................................11

2.1.4.1.2 Preparing reports......................................................................................................12

Kularat hnaM . P .D .S .C .vi

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2.1.4.2 Ekala LECO Training Centre.........................................................................................12

2.1.4.2.1 Meter testing laboratory...........................................................................................12

2.1.4.2.2 Tests apply on Energy meter...................................................................................16

2.1.4.3.1 Transformer Testing................................................................................................17

2.2 Training Experience in Ceylon Electricity Board.........................................................................19

2.2.1 Samanalawewa Hydropower Plant.........................................................................................19

2.2.1.2 Surge Chamber...............................................................................................................19

2.2.1.3 Power house....................................................................................................................20

2.2.1.5 Active power control......................................................................................................20

2.2.1.6 Reactive power control...................................................................................................20

2.2.1.7 Power Transformers.......................................................................................................21

2.2.1.8 Switchyard......................................................................................................................21

2.2.1.9 Auxiliary supply.............................................................................................................22

2.2.1.10 Governor.......................................................................................................................22

2.2.1.10 Battery bank..................................................................................................................22

2.2.2 Kelanithissa Thermal Power Plant.........................................................................................22

2.2.2.1 Small Gas turbines (GTs)...............................................................................................22

2.2.2.2 Synchronous Condenser Mode.......................................................................................23

2.2.2.3 Starting of Small Gas turbines (GTs).............................................................................23

2.2.2.4 115MW Large Gas turbine (GT)....................................................................................23

2.2.2.5 GIS..................................................................................................................................23

2.2.3 Kelanithissa Combined Cycle Power Plant............................................................................24

2.2.3.1 Starting the GTs..............................................................................................................24

2.2.4 Spugaskanda Power Plant......................................................................................................25

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2.2.4.1 Overview of the Plant.....................................................................................................25

2.2.4.2 Fuel oil System...............................................................................................................26

2.2.4.3 Engine modules..............................................................................................................26

2.2.4.4 Turbo Charger.................................................................................................................27

2.2.4.4 Generator........................................................................................................................27

2.2.4.5 Switch yard of the Power plant.......................................................................................28

2.2.4.6 Maintains........................................................................................................................28

2.2.5 System Control Centre...........................................................................................................29

2.2.5.1 System Stability Limits..................................................................................................29

2.2.5.2 System Operation...........................................................................................................29

2.2.5.3 Operation Planning.........................................................................................................30

2.2.5.4 Under Frequency Load Shedding...................................................................................30

2.2.6 CEB Head office Generation and Transmission Planning division.......................................31

2.2.6.1 Planning and Demand forecasting..................................................................................31

2.2.6.2 Generation Planning.......................................................................................................32

2.2.6.3 Transmission Planning...................................................................................................33

2.2.6.4 The load flow analysis....................................................................................................33

2.2.7 Rathmalana and Pannipitiya Grid Sub Station.......................................................................34

2.2.7.1 Rathmalana Grid Sub Station.........................................................................................34

2.2.7.3 Components in substations.............................................................................................35

2.2.7.4 Power Transformer.........................................................................................................35

2.2.7.5 Protection method of Power Transformer......................................................................36

2.2.7.5.1 Hot spot temperature...............................................................................................36

2.2.7.5.2 Bucholz relay...............................................................................................................36

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2.2.7.6 On load tap changer........................................................................................................36

2.2.7.7 Dehydrate filter breather.................................................................................................36

2.2.7.8 Pressure relief Valve.......................................................................................................37

2.2.7.9 Switching in a switch yard..............................................................................................37

2.2.7.12 Circuit Breakers............................................................................................................37

2.2.7.13 Current Transformers...................................................................................................38

2.2.7.14 Potential Transformers.................................................................................................39

2.3 Training Experience in Amithi Power Consultants (Pvt) Ltd.......................................................40

2.3.1Testing and Measurement.......................................................................................................40

2.3.1.1 Insulation Testing...........................................................................................................40

2.3.1.2 Cable Insulation Testing.................................................................................................41

2.3.2.3Relay testing....................................................................................................................42

2.3.2.3.1 Secondary injection and Primary injection test on relays........................................43

2.3.3 Capacitor Bank Designing.....................................................................................................44

Applicable Standard...................................................................................................................44

2.3.3.1 Energy survey Results....................................................................................................44

2.3.3.2 Recommendations..........................................................................................................45

2.3.3.3 Calculation and the Size of the Capacitor bank..............................................................45

2.3.3.4 Phase balancing..............................................................................................................47

2.3.4 Lightning Protection System Designing................................................................................48

2.3.4.1 Direct lightning...............................................................................................................48

2.3.4.2 Indirect lightning............................................................................................................48

2.3.4.3 Protection of structures against lightning.......................................................................48

2.3.4.4 Risk Level assessment for the building..........................................................................49

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2.3.4.5 Methods of Air Termination System as per IEC............................................................51

2.3.4.6 Main Components of lightning protection system.........................................................53

2.3.5 Thermal Imaging....................................................................................................................55

2.3.5.1 Concept of Thermal Imaging..........................................................................................55

2.3.5.2 Importance of thermal imaging......................................................................................55

2.3.5.3 Suitable for Thermal imaging in.....................................................................................56

2.3.5.4 Thermal imaging in LV switch board and Cables..........................................................57

2.3.5.4 Consider the following analysis of thermal images........................................................57

2.3.6 Electrical installation design..................................................................................................60

2.3.6.1 Lighting design And Switch placing.................................................................................i

2.3.6.1.1 Factors and procedure to consider while lighting design...........................................i

2.3.6.1.2 Utilization factor.........................................................................................................i

2.3.6.1.3 Maintenance factor....................................................................................................ii

2.3.6.1.4 Suitable lighting and fittings.....................................................................................ii

3. Conclusion...........................................................................................................................................iv

ANNEX 01..........................................................................................Error! Bookmark not defined.

Kularat hnaM . P .D .S .C .x

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List of Figures

Figure 1.1 – Product (Electricity) flow of electricity 03Figure 2.1 – Isolation and Earthing of lines 07Figure 2.2 – Insulated T-Off Connectors 09Figure 2.3 – Pre Insulated Joints 09Figure 2.4 – Pre Insulated Bimetal Lug 09Figure 2.5 – Uninsulated Joint 09Figure 2. 6 – H Type Compression Connector 09Figure 2.7 – Hydraulic Crimper 09Figure 2.8 – Ratchet Lever Hoist 09Figure 2.9 – Surge Arrestor 09Figure 2.10 – Structure of Branch 10Figure 2.11 – Construction work done by the LECO 10Figure 2.12 – Procedure of construction 11Figure 2.13 – Disk of energy meter 15Figure 2.14 – Megger test on transformer 18Figure 2.15 – Power plant 19Figure 2.16 – Dame Section 19Figure 2.17– Surge Chamber 19Figure 2.18 – AVR 21Figure 2.19 – Samanalawewa Switch yard 21Figure 2.20 – Small GT in Kelanithissa 22Figure 2.21– HRSG 24Figure 2.22– Sapugaskanda Power Station Engine Arrangement 23

Figure 2.23– Fuel oil System 26Figure 2.24 – Turbo charger system 27Figure 2.25 – Self Exciter 28Figure 2.26 - Transmission planning process 32Figure 2.27 – WASP-iV Software 33Figure 2.28 – Model in PSS 34Figure 2.29 – SF6 breaker 38Figure 2.30 – Current Transformer (CT) 38Figure 2.31 – Potential Transformer (CVT) 39Figure 2.32 – internal arrangement of Megger tester 40Figure 2.33– testing insulation levels of cables 41 Figure 2.34 Digital Insulation Tester 42Figure 2.35_Secondary Injection test on relay 43

Kularat hnaM . P .D .S .C .xi

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Figure 2.34_ Measured Active power and Reactive Power Apparent power against Time 44Figure 2.37_ Measured each phase currents against Time 45Figure 2.38 – Phaser diagram before and after install the capacitor bank 45Figure 2.39 – Measured each phase currents against Time 47Figure 2.40 – Capacitor 47 Figure 2.41 – Selection of lightning protection system 49Figure 2.42– Calculation of collection area 50Figure 2.43– Protective angle method 51Figure 2.44– Rolling sphere method 52Figure 2.45– Distribution T/F in firing 54Figure 2.46– Power T/F firing 54Figure 2.47– Thermal Images of Electrical Systems 55Figure 2.48– Thermal image of cable 57 Figure 2.49– Digital image of cable 57Figure 2.50– Thermal image of LV breaker 58Figure 2.51– Digital image of LV breaker 59Figure 2.52– Lighting design 60

List of TablesTable 1.1- Training Establishments 01

Table 2.1 – percentage error tests on Energy meter 17

Table 2.2 – System stability limits 29

Table 2.3 – Under frequency load shading schedule 31

Table 2.4 – Cable insulation levels 41

Table 2.5 – specific voltage level for insulation testing 43

Table 2.6 – Energy survey result summery 44

Table 2.7 – System variable before and after capacitor bank installation 46

Table 2.8 – Standards for lightning protection design 48

Table 2.9 –Max allowable Temperatures for LV panels. 56

Table 2.10 – Cable temperature Analysis in FLIR software 57

Table 2.11 – LV panel temperature Analysis in FLIR software. 58

Kularat hnaM . P .D .S .C .xii

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1. Introduction to the Training Establishment

This industrial training programme module had specially been allocated in to two main sessions for

Electrical Engineering students, Total period for the industrial training program was 24 weeks and it

was divided in to two main sessions with a period of twelve weeks for each according to the schedule

given by the Industrial Training Division of Faculty of Engineering, University of Moratuwa.

Following table shows exactly time periods of the training Programme.

Table 1.1- Training Establishments

1.1 La

nk

a

Electricity Company (Pvt) Ltd

1.1.1 Introduction to LECO

LECO is the only one privet organization of Sri Lankan power sector having a license to carry out

power distribution function within the country. By purchasing power (11kV from primary substations)

from Ceylon Electricity Board and distribute to the customers in (400V) coastal belt from Negombo to

Galle excluding Colombo city, Dehiwala and Mount Lavinia. Now a day LECO area is in operation in

their seven branches, and got the authority to provide electricity supply to Kotte, Nugegoda, Kelaniya,

Moratuwa, Galle, Kaluthara and Negombo areas. Provides its service with 7 Branch Offices, 24

Customer service Centers, 2 Main Stores, Meter Test Lab, Technical Training Center and Transformer

Repair Workshop.

Kularat hnaM . P .D .S .C .1

Session Training Establishment Allocated Period

1 Lanka Electricity Company (Pvt) Ltd 4 weeks

Ceylon Electricity Board 8 weeks

2 Amithi Power Consultant (Pvt) Ltd 13 weeks

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1.1.2 History of the LECO

In 1984 LECO started their distribution functions in some cities of western and Southern coastal belt

between Negombo and Galle.By recognizing the weaknesses of Local distribution functions carried by

CEB such as unreliability of supplies, high electrical losses, unsatisfactory revenue collection

procedures and the required investments for system improvements, by avoiding these inconvenients

and unsatisfactories as a result of that the Lanka Electricity Company (Pvt) Limited was established in

September 1983 under the Companies Act.

1.1.3 Vision and Mission of LECO

Vision

“Enjoy being the light for the lives of people through innovative eco-friendly business”

Mission

“To provide the best energy solutions to the society through continuous innovations”

1.1.4 Organization Structure of the LECO

Organization structure of the LECO is given in ANNEX 01 (Organization Structure of LECO)

1.1.5 Present Performances and Strength of the LECO

LECO won the National Quality Award in 2001 and Ceylon Petroleum Corporation Award

best energy conservation project.

Maintaining supply voltage at customer premises within 216-244 volt (230 V±6%)

Voltage drop is reduced by using more distribution transformers in low capacities instead of

using high capacity transformers and long distribution cables.

LECO has reduced its system losses to 5.5%, which remained at over 20% when electricity

distribution was carried out by local authorities.

LECO introduced for the first time in Sri Lanka the use of Arial Bundled conductors (insulated

conductors) for low voltage (11KV and 400V) distribution. There by reducing customer

outages significantly. This will help to reduce losses due to way leaves and unauthorized

tapping. This is also an achievement because to give this type of supply at consumer ends

planning and maintains should be done properly. As a business organization while profit

making, satisfaction of consumer also were been taken in to consideration.


CEB GenerationIndependent power producers

Small power purchase

CEB Distribution 4 Regions LECO distribution

Transmission network

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1.1.6 Profitability of the LECO

Company should have profits to run the company even at the beginning LECO runs as unprofitable

institution now it is a profitable company. This is due to their best business strategy by reducing

unwanted losses in their whole network of distribution and net work in the organization.

1.1.6 Usefulness of LECO to Sri Lankan Society

As a power supplying company their role in the country is appreciable for taking every possible effort

to supply much more reliable Electricity to consumer premises. Customers are treated well and

presently they are planning to improve the efficiency and quickness of their service. LECO is using

new technologies to enhance the quality and reliability of the power supply.

1.2 Ceylon Electricity Board

1.2.1 Introduction to CEB

Ceylon Electricity Board controls one of a major consumer requirement which is Electricity. As an

island wide large organization they bare the license and responsibilities of fulfilling the electricity

demand of whole country. This is operated under the Ministry of Power and Energy. A large portion

of the power generation, totally whole transmission functions and a large portion of distribution are

done by CEB. So the CEB acts main role in Power sector inside the country any aspect of

developments and civilization is always combined with Electricity therefore their functions are impact

for the development of the country.

To supply as possibly maximum service and for ease of management CEB has divided in to three

divisions according to their functionalities known as Generation, Transmission & Distribution

Divisions and distribution division has four distribution regions known as Colombo, Kandy, Galle and

Anuradhapura.

The product flow of electricity is as follows. Cash flowing is also in same but reverse direction its

happening. Also in consumer points are also produce electricity after introduce the two way metering

using solar photovoltaic and other means. It is negligible compared to total power flow.


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Figure 1.1 – Product (Electricity) flow of electricity

1.1.2 Organization Structure of the CEB

The organizational structure and hierarchical levels are shown in ANNEX 01 (Organization Structure

of CEB).

1.2.3 Present Performances and Strength of the CEB

The electricity transmission part is totally owned to CEB, large portion of the electricity generation is

also done by CEB. The large hydro complex such as Mahawelli and Laxapana has the most profit

making hydro power plants. Existing thermal capacity is 517 MW and hydro capacity is 1205 MW.

900 MW of Coal Power Plant is committing in Puttalam and 150 MW of committed hydro capacity in

Upper Kotmale. CEB is governed under Ministry of Power and Energy to supply reliable and quality

electrical power for the development of the country and improve the living quality of lives with all

about 14000 employees in different levels and skilled. Ceylon Electricity board got large number of

valuable assets spread all over the country and this is one of a largest organization in Sri Lanka.

1.2.4 Usefulness of CEB to Sri Lankan Society

CEB is so important to the Sri Lankan society since it is the governing authority of Sri Lankan

electricity Generation, Transmission and Distribution. All the communication systems, most of

functions in various kind of industrial, domestic and public are depending on the electricity supply. So

the reliable and efficient electricity supply is essential factor to the Society. This organization serves

the people in Sri Lanka by delivering an efficient and reliable supply to the community. Activities and

decision taken by this organization will directly affects to the economical development of the county.

This company always try to serve and satisfy the customers first and then they get the benefit of it.


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And this company has created number of job opportunities and it helps to develop the life stand of

people. Therefore this company is very important to the Sri Lankan society and people can get a lot of

benefits through this company.

1.2.4 Suggestions for improvements

Should avoid political recruitments and make the opportunity for only skillful workers. As I heard

there are many other unsuitable political involvements inside this organization and so many external

effects from many ways. This all involvements are as in past the organization will put in to trouble. At

present organization has well organized management structure as suitable for this type of organization

this. will make proffits Introduce new software systems to do the transmission network analyzing

tasks, forecasting tasks and other requirements.

Introduce an evaluation procedure for the workers and engineers to enhance their efficiency.

There should be a group to study and introduce new technologies by looking at the world.

There should be a quick and reliable good and tools supply procedure in a situation such as breakdown

in grid substation etc…

1.3 Amithi Power Consultants (Pvt) Ltd

1.3.1 Introduction to APCL

Amithi Power Consultants is one of a leading electrical design firm in Sri Lanka. Many types of high

voltage and low voltage design consultants are handled by APCL. So many local and also foreign

projects have design and consulted by APCL. As the owner and the managing director of this

company Mr. Rienzie Fernando does a great service in the company to leading and giving instructions.

1.3.2 History of the APCL

Mr. D.G. Rienzie Fernando, owner and the managing director of this company has established this

company in 1996 after retiring from the post DGM of CEB. Since that APCL has successfully

completed large number of projects and services in electrical field.

Vision


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“Strengthen the capabilities of Sri Lankan Engineering professionals to the International Standards by

improving the status of Sri Lankan Electrical Engineering sector through continuous efforts”

Mission

“Cater the vacuum of consulting service in and out of the island, in the relevant electrical fields”

“To spread our wings over a foreign market to work to fill the increasing gap of engineering services”

1.3.3 Organization Structure of the APCL

The organizational structure is shown in ANNEX 01 (Organization Structure of Amithi power

consultants).

1.3.4 Present Performances and Strength of the APCL

This firm supplies their services in the electrical sector locally and internationally some of very giant

project which APCL has handled are Brandix Apparel City in India, Niyagala Open University

Project, Design and project supervision of Embilipitiya Substation and the transmission line. Lighting

Sri Lanka- Hambantota Project, Senok Wind Power Station, Ambewela wind Power Station. Under the

guidance of Mr.Rienzie Fernando and director board

APCL team of expertise is always in alert about new technologies and latest updates of standards

about electrical engineering. These days they are doing a power plant design project in Iraq.

Apart from that Safety audits, electrical testing are also performed

1.3.5 Profitability of the APCL

Since the beginning of this organization was a profitable organization due to the dedication and

determination of the all staff members.

1.3.6 Suggestions for improvements

There is some points in my view to improve the profitability and that it does not going to compete

with other organizations. It performs its job which they got and do not run for projects. And they do

not carefully about spreading their name over the country. That is over time hours are not given to the

employees and this would effect to motivation of employees worse.


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1.3.7 Usefulness of APCL to Sri Lankan Society

APCL supply high quality and reliable services of electrical engineering field. They contribute to earn

foreign currency in to our country because they are involved in foreign projects also. Most important

thing is that this place makes skilled professionals in Electrical Engineering field by providing

working opportunities to make their carrier path while earning their salary.

2. TRAINING EXPERIENCES

2.1 Training Experience in Lanka Electricity Company (Pvt) Ltd

2.1.1 Maharagama LECO Depot

2.1.1.1 HT maintenance

In any kind of maintains in their HT lines that the depot should ask for a work permit. Control centre

plan interruptions and allows them to do maintains the HT lines as minimum no of consumer are

affected for the power cut and CSC are received docket by mentioning every details. There is a sketch

of positions to be switched to isolate required portion of net work by load break switches. After

completed the maintain network is re arranged according to control center information they always in

connection with control centre through radio communication links.

At maintain procedure first they isolate through LBSs, the required line part and earth each end of line

through bare conductor connectors. At an end of line all three phase lines are connected conductors

and clamped to single conductor and grounded.


Single Line Drawing of the Network Near Maintain

3 Phases Earthing Points

Required Portions to Isolate for Maintain

Load Break Switches on poles

1

2

3

33

2

1

3

1

1

12

3

3

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Figure 2.1 – Isolation and Earthing of lines

There are reasons to consider for additional protection using earth the conductors even isolated lines.

If voltage is generated in low voltage side of consumers it will stepped up into 11 kV lines.

If another 11kV line above, induced voltages may be in the lower line.

Normally HT lines are induced due to inductive behavior and may charge due to capacitor

behavior at some points.

The load break cutoff may reconnect (rare) due to unusual occurrences.

2.1.1.2 Consumer Breakdown maintains

Always depot Technical staff is in alert about consumer calls about their supply problems. They are

ready to response for these interruptions as possible as quickly normally these consumer breakdowns,

maintains and complains are regards as follows,

Burning of MCB due to high current flowing

Energy meter related requests

400V Lines, Poles and consumer supply line related requests


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2.1.1.3 Field billing

According to the supply connection or on the other word according to the tariff, customers are

categorized as domestic, general purpose, industries, temporary and religious.. Domestic bills are

counted by the revenue officer and bulk consumer bills are prepared by customer service

superintendent.

2.1.1.4 Disconnecting process

Branch office informs the list of disconnections to the Customer Service Centre with the ACC No,

substation (transformer), address, name, and bill amount. The bill is checked in the computer at the

CSC also before going to disconnection to see whether he paid the bill at a just a moment before. After

disconnecting the bill is handed over to the consumer. When that bill has paid, the branch will inform

the Customer Service Center to reconnect it here LECO charge additional fine for the inconvenience.

2.1.1.5 Breakdown registry

Consumer complains of breakdowns may be a tree fallen down to the line, MCB has burnt, meter is

not working, or No supply etc… That complains are recorded with persons went to resolve the

problem, vehicle, day & time, place, equipments used etc…

2.1.1.6 Equipments and Materials use in LECO Depots

There was large number of equipments and materials in the depot store room, few of them are as

shown in below

Insulated T-Off Connectors

These are suitable for line tapping from aerial bundle conductors. It is safe

even live conductors are also possible to tapped. Normally use to tape to

connect consumer supply lines. Figure 2.2 – Insulated T-Off Connectors

Pre Insulated Joints

These are suitable for joining two L.V. bundle conductor lines in mid span. After

stripping of conductors as length marked on the body of the joint, inserted two

conductors in both end and use hydraulic crimper to tighten.


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Pre Insulated Bimetal Lug Figure 2.3 – Pre Insulated Joints

These are used for connecting bundle conductor to a copper pad or to transformer

studs. After stripping of conductor as length marked on the body of the joint,

inserted the cable end and use hydraulic crimper die to tighten.

Figure 2.4 – Pre Insulated Bimetal Lug

Uninsulated Joint

These are suitable only for uninsulated neutral conductor joining. Same

crimping die used on the neutral and phase joints. Figure 2.5 – Uninsulated Joint

H Type Compression Connector for Overhead Lines

These are used to tap off uninsulated ABC conductors

Figure 2.6 – H Type Compression Connector

Hydraulic Crimper Ratchet Lever Hoist Surge Arrestor

Used in above mention jointing

Figure 2.7 – Hydraulic Crimper Figure 2.8 – Ratchet Lever Hoist Figure 2.9 – Surge Arrestor

2.1.2 Nugegoda LECO Branch Office

A branch office is doing all stuff of works under the supervision of the Branch Engineer. Normally at

upper levels of organization structure Engineers are having large experiences they have here in

industry for a long time. Basically branch office carry out LV Planning, handling construction works,

job costing, Estimation preparation, route survey, customer services, service from accounting division,

and administrative functions inside the office etc. There are several depots under any Branch office all

super vision of depots are also under the branch office.


Branch Manager

Branch Engineer

Electrical Engineer

Chief technical officer, draftsman and that staff

Chief Accountant

Computer SupervisorACC/assistant revenue collectionACC/assistant General

Administrative officer (head)

Administrative staff

Staff

LECO Construction works

LECO RequiredSystem DevelopmentSystem Maintains

Consumer RequestedNew connection Shifting poles Meter changingChange connection etc.

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Figure 2.9 – Structure of Branch

2.1.2.1 LECO Construction work

Figure 2.10 – Construction work done by the LECO

Branch office involves in planning, development, maintain of LV System and to provide the consumer

requested services

2.1.2.2 Planning & construction

Branch office considers the planning of the LV distribution system (400V network). According to the

level of work, who involves in the planning surveying and construction is dependent. Their Surveying,

job costing of new constructions are doing under Electrical Engineer and hand over to the branch


Consumer request Route Survey Estimation by TO Recommendation and approval Select a contractor

File is sent to CSCConstruction

Figure 2.12 – Procedure of construction

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engineer for the approval. Contribution from the branch office for the procedure of construction is as

follows.

According to the consumer request, a survey is done in order to identify how the job to be done

according to the location if only necessary.

Once the survey completed legal permissions should be taken from required authority to place poles

and to erection of lines, this takes much time and while job costing is done and estimation prepared.

Then with the approval a contractor is selected and through the CSC constructions are done.

2.1.2.3 Job Costing

Standard cost manual is referred in cost estimations to get the standards cost given by the PUCSL. In

the standard cost manual there are prices of each and every one of items used in distribution

construction. Cost can be basically categorized in to four types, Material cost, Labor cost, and

Construction cost and Over head cost. For each specified jobs these costs are represented using above

4 types of costs and they are denoted by Index called KIT (KIT numbers). According to the job there

is the cost value in the cost manual.

MKIT - KIT Index to denote the Material

LKIT - KIT Index to denote the Labor

CKIT - KIT Index to denote the Construction cost

VKIT - KIT Index to denote the Variable cost (Over head cost)

By entering theses KIT indexes according to the job we can calculate the cost for any construction

using computer software called “PRONTO” or possible to calculate the cost manually also. PRONTO

make it easy the jobs costing.


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2.1.2.4 LV Planning

Planning the LV distribution systems after secondary substations in the other word 400V network

planning, this is done to supply recommended voltage level at the consumers end by considering the

length of conductors and consumer loads. Hence the voltage drops of conductors are calculated. If not

satisfied the voltage levels new secondary substation or tie line is proposed to supply quality

electricity to consumers.

2.1.3 LECO Head Office

2.1.3.1 Engineering Division

Basically this division does the system development, procurements handling for the following. For the

system development process they forecast the future energy demand and the other thing is planning

the network as suitably for distribute that energy. Then do the load flow analysis to identify the system

under worst cases and identify the required upgrades in the network. If the present primary substations

are not enough then have to go for new primary substations. For the above upgrading financial

analysis do using the above reports.

2.1.3.2 Load forecast

There are four possible method/ models for Load forecasting

Judgmental method

Time trend Model

Regression Model

Econometric Model

LECO uses time trend and regression models, in this process present and past 10 years data uses and

assuming liner system forecasted the future demand.

2.1.3.3 Planning

Under the planning network of 11 kV system is modeled and then do the load flow analysis to plan the

network system as suitably. Network spread over LECO area have mapped in the mapping process


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GPS is used to find the exact coordinates of the locations. For that they have equipment which can

communicate with satellites. At the construction of each poles, transformers, LBS etc they are

included in to map with their details.

2.1.3.4 Load flow analysis

Load flow analysis is done for the overall peak because peaking time for each transformer is different.

So the maximum demand of each transformer is multiplied by a factor called “contribution to the

peak” (65% for industrial, 80% for domestic). Then get the addition of loading of all the transformers

at the peak and compare with the actual feeder loading near the primary substation.

Then we can use the voltage near the primary substation, active and reactive power of each

transformer as inputs to the software PSS (Power System Simulator). And run the software to find the

required details such as feeder loadings, voltage drops, and losses. If there are problems with results,

simulate the network with available proposals to avoid those issues. In this way the load flow analysis

is done for five years future while increasing the loads of transformer according to the forecasting and

proposed solutions to the problems and unwanted system behavior.

2.1.4Operation Division

Operation division does the maintaining of the present system to supply consumer required Electrical

energy in efficient manner.

2.1.4.1Distribution Control Centre

2.1.4.1.1 Task of system control centre

Whole 11kV LECO distribution network system is controlled according to the command given by this

centre current status of the whole distribution system can be seen from the control centre. Each and

every one of breakdowns and interruptions and repairs are informed to here according this information

always they update the single line diagram (MIMIC panel).

Scheduled interruptions are requested by branch officers to the control centre. Then they study the

situation and select the optimum way to shift loads and isolate power lines as possible as minimum the

number of consumers affected from the interruption and the day which they allow. For giving


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permission for interruption they prepare a switching instruction and send them to the depot through

branch office.

2.1.4.1.2 Preparing reports

Service call report and Electricity supply outage reports are prepared here

Service cal report

Service cal report contains all the service calls and they are sorted in few categories as flows.

Branch wise

Customer Service Centre wise

Type of fault wise

Time of the day wise

They check number of calls per 100 consumers and average restoration time. It includes detailed

report and group of each branch.

Outage report

Outage report contains all outage details both due to interruptions and breakdowns. Using those

details, they calculate following reliability performance measurement indices.

SAIDI - System Average Interruption Duration Index

SAIFI - System Average Interruption Frequency Index

CAIDI - Consumer Average Interruption Duration Index

MAIFI - Momentary Average Interruption Frequency Index

Each index is calculated for each and every branch. Also get final average value for company. This

report can be used to get the whole idea about the performances of the LECO distribution system.

2.1.4.2 Ekala LECO Training Centre

2.1.4.2.1 Meter testing laboratory

At the meter testing place where they repair the faulted energy meters by replacing the damaged parts

with relevant parts of other broken meters. Finally testing and small adjustments has done in order to


Damper Magnet

Magnetic Bearing

Spring Suspension

Disk

Jail Bearing

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send for the use. In the meter testing lab there are testing benches, that benches for testing more meter

at simultaneously, only analog meters are tested in this type of test bench.

In this laboratory bulk meters are programmed also.

Figure 2.13 – Disk of energy meter

Disk is divided into 100 parts and the disk is on a magnetic repulsion force. Other bearing type is jail

bearing which has a small point at the end of the shaft and directly contacted with the base by means

of these friction on rotation is reduced as maximum possible. The meters are mounted on the meter

testing bench. And small adjustments are done. Permanent magnet is pushed towards the disk to slow

down the speed, pulled to speed up. Voltage coil is adjusted with low load and no adjustments for

current coil.

2.1.4.2.2 Tests apply on Energy meter

Single phase and three phase mechanical and digital meters are tested here to confirm a single

phase meter 3 tastings are conducted.

Percentage error test

Creep error test

Dial test


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2.1.4.2.2.1 Percentage error test

This test should be done by applying rated voltage with different currents and power factors as shown

in below. If the required error percentage is not meet, then adjust the Voltage and current coil

positions by rotating the screw given in the energy meter and again do testing until reach the required

error percentage or below that level.

Table 2.1 – percentage error tests on Energy meter

Applying current power factor (pf) Condition for confirmation

5% base current Unity ok if error is between in ±2.5%

100% Base current Unity ok if error is between in ±2%

Maximum current Unity ok if error is between in ±2%

100% Base current 0.5 lagging ok if error is between in ±2%

2.1.4.2.2.2 Creep error test

Apply 80% to 110% of rated voltage with no current input to the current coil about 20 minutes. If the

disk cannot complete at least single revolution meter is considered as acceptable for creep test (no

creep error). If the disk completed one or more rotation adjust the damping magnet and test again until

meet the required error less condition.

2.1.4.2.2.3 Dial test

Apply current and rated voltage and all testing meters are connected to flowing 1kWh and counting

the revolutions of the disk to ensure weather the applied energy is indicated correctly and the indicated

in registry correctly.

2.1.4.3 Transformer repair centre


Megger tester

Transformer Cover

Phase Terminals

Primary Winding

Secondary Winding

Neutral Terminal

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2.1.4.3.1 Transformer Testing

2.1.4.3.1.1 Megger test

Transformer were testing to find winding insulation failure using megger tester resistance was

measured between each winding by applying high voltage

Check the Megger reader before test. Then Keeping voltage at 2500 V

Test HV wingding to earth insulation level.

Test HV wingding to LV wingding insulation level Keeping voltage at 1000 V

Test LV to Earth insulation level 500 or above insulation level is ok

Figure 2.14 – Megger test on transformer

2.1.4.3.1.2 Ratio test

400 V is applied to the HV side and

Check the voltage of phase to neutral for each phase.

Phase to phase for each tap position of the tap changer.

For each phase to neutral voltage should same

For each phase to phase voltages should be same


Resavoiur

Power tunnel

Surge chamber

Portal Valve house

Penstoke

Power house

Tail race

Intake

Clay Core

Rock fill

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2.2 Training Experience in Ceylon Electricity Board

2.2.1 Samanalawewa Hydropower Plant

Samanalawewa hydro power plant is possible to contribute of 120MW normal power output to the

national power system. Power generation is done by using 60MW salient pole two synchronous

generators. 10.5 kV output from generators are setup into 132kV using two power transformers.

Through the switch yard this is connected to Balangoda and Embilipitiya Double circuit lines.

Power plant

Following shows a brief sketch of power plant

Figure 2.15 – Power plant

Dame


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Figure 2.16 – Dame Section

Rock fill clay core type dam has maximum height of 100m and length of 480m

2.2.1.2 Surge Chamber

Figure 2.17– Surge Chamber

The surge chamber is to bear the sudden pressure impact when the main inlet valve (MIV) is closed at

the power house. Otherwise the penstock may be damaged. There are different types of surge

chambers, this surge chamber is orifice type one.

2.2.1.3 Power house

Water coming through the pen stoke is blocked by main inlet valve (MIV). The flow of water is

controlled due to power variations by the wicket gates. There are three turbines to produce electricity.

The type of turbine is Francis. Name plate data of turbine and generator are as follows.

2.2.1.5 Active power control

According to variation of load connected to transmission net work is varying time to time therefore

system frequency is trying to change simultaneously. It is possible increase or lower the power output

by varying mechanical input given to the generator. For this Water flow is controlled by turbine


GENERATOR

Output: 70.6MVA/60.1MW

Output voltage: 10.5kV

Power factor: 0.85

Rated Speed: 500 rpm

Excitation: 120 V and 1400 A

12 poles salient pole type synchronous

generator

TURBINE

Type: Francis

Speed: 500 rpm

Output: 70.2MW

Vertical shaft turbine

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governor. Wicket gates are opened when more active power is required. This is a closed loop system

coupled with the speed of the turbine.

Samanalawewa power station is possible to use for frequency controlling when water level is

sufficient in the reservoir.

2.2.1.6 Reactive power control

AVR is used to regulate the terminal voltage in a set value. Excitation is increased when the terminal

voltage is decreased. Excitation is given by using a battery bank at the starting of generator and then it

is switch in to excitation transformer of the generator output.

The excitation for the rotor field is obtained from a 10.5-kV/270-V 600-kVA transformer rectified by

thyristors and controlled by voltage regulator. The star point of the stator windings is earthed through

a 8.5-kV/250-V transformer rated at 24 kVA.

Figure 2.18 – AVR

2.2.1.7 Power Transformers

There are two main power transformers which are use to step up the generated voltage 10.5 kV up to

132 kV one for each generator. They are71 MVA transformers vector group is YND11 and cooling

system is ONAN/ONAF.


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2.2.1.8 Switchyard

The 132kV double circuit transmission lines are connecting from Embilipitiya and Balangoda

through switchyard. Simple single line sketch of switch yard is as follows. (Even here is not consist all

equipments)

Figure 2.19 – Samanalawewa Switch yard

Switchyard consists of two basbars ,SF6 circuit breakers, isolators, surge arrestors etc. The

breakers in the switchyard can be connected to either busbar. Local control is also available for

emergency and maintenance purposes. A mechanical interlock system is provided through out the

electrical system.

2.2.1.9 Auxiliary supply

Auxiliary supply means power required for the plant premises for lighting, maintain for office etc. For

the more reliability there are three systems available auxiliary transformers for the station gives output

of 400 V. in addition there is a stand by auxiliary transformer. In emergency case or blackout there is a

diesel generator to give station supply.

2.2.1.10 Governor

Governor mainly consists of regulator, actuator and a SSG. The regulator is of the PID type. It consists

of speed sensing circuit and PID circuits and a power amplifier circuit. When the unit speed changes

the actuator immediately responds to the electrical signal from the regulator which converts the speed


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change of the unit to the electrical signal and operates the converter to control the guide vane

servomotor. The guide vane opening is changed to change the generator output so as to keep the unit

speed at the rated speed.

Speed sensing is provided by a SSG which is installed at the top of the generator housing.

The main governor characteristics:

Range of speed droop: 0-10%

Governor dead time: less than 0.25 sec

SSG frequency: 1000 Hz

2.2.1.10 Battery bank

Batter bank is essential for a power station. Battery voltage is120 V. those are NiCad (Nickel

cadmium) batteries.

Excitation at the start

Turbine auxiliaries

Transformer auxiliaries

Governor auxiliaries

2.2.2 Kelanithissa Thermal Power Plant

Colombo is the main load centre of the Sri Lanka therefore it is very better the power station near the

load centre. Kelanithissa power station is in the Colombo. In Kelanithissa power station there are six

20MW small gas turbines and 115MW one large gas turbine generator (GT). One of small turbine is

damage heavily and out off working. Total available capacity is 215 MW even though they are not

possible to work in their full load capacity. Only two of GTs was running in synchon (synchronous

condenser) mood to supply KVar to the system.

2.2.2.1 Small Gas turbines (GTs)

Compressor compressed inlet air and insert in to combustion chamber atomized diesel fuel particles

are mixed with compressed air. This mixer diesel is ignited in combustion chamber. From the

combustion process makes a high pressure and high temperature output this is directed to turbine and


Generator

Baring motorcompressorStarting diesel engine exhaust airDisengaging gear boxturbine Disengaging gear box

Inlet airFuel inlet Combustion chamber

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rotate the turbine. Then it couples to a synchronous generator so the electrical power is generated. This

is the normal energy conversion process in any kind of gas turbine.

Apart from that, this20 MW small GTs having disengaging gear box therefore they are possible to run

in synchon mode.

Figure 2.20 – Small GT in Kelanithissa

Due to heavy weight of the rotor if it allows to cool gas turbine that the rotor may sag and again

starting may dangers and may cause damages to the machine. This is avoiding by a process called

baring. Baring is even if the gas turbine shut down its rotor is regularly rotate at very low speed to

avoid this sagging.

2.2.2.2 Synchronous Condenser Mode

Sometimes the generators run in this mode. In this mode generator provide reactive power requirement

to the national grid. While in this mode generator absorbs active power from the grid and generate

reactive power to maintain the magnitude of the voltage. At this stage turbine shaft is departed from

the generator shaft. Then the generator shaft rotates alone by taking active power from the grid.


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2.2.2.3 Starting of Small Gas turbines (GTs)

At the starting of these GTs up to 100rpm speed they are running using a diesel engine. At this speed

fuel atomized gas injects to the combustion chamber and start the firing. Until come to 3000rpm diesel

engine does not disengage the gas turbine and then the diesel engine is removed. Then turbine is speed

up until a speed of 5100 rpm is acquired then synchronize machine to grid.

2.2.2.4 115MW Large Gas turbine (GT)

This 115MW generator is also having same operation principle, differences are it consists of 1MW

high torque motor to start the GT and due no disengaging gear box to disengage generator and turbine.

Baring and other all process are required in here also. Starting process of this GT is as same as the GT

start in combined cycle power plant GT.

2.2.2.5 GIS

In plant premises there are 220kV and 132kV two GIS. GIS means gas insulated switch, all the

switching functions are possible as in normal outdoor switch yard. This type of GIS is most suitable

for urban area where less space taken for the system. Insulation gas medium is SF 6. Breakers, isolators

and bas bars all components are inside the pressurized SF6 medium.

2.2.3 Kelanithissa Combined Cycle Power Plant

In Kelanithissa Combined Cycle Power plant synchronous generator coupled to the gas turbine

generates with max power output of 115MW. Exhaust of that can run a steam turbine generator and

which has max power of 50MW. Main GT is same as the large GT in Kelanithissa power plant. In

combined cycle power plant the special unit is the HRSG (Heat Recovery Steam Generation) and

steam turbine. Exhaust flue gas from the gas turbine contain large heat energy. That heat energy is

extracted in HRSG to run steam turbine without wasting that heat energy


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Steam power generation

Figure 2.21– HRSG

2.2.3.1 Starting the GTs

First GT is running using 1MW (cranking) motor into a 27% of its full speed (The rated speed of the

turbine is 5100 rpm) and then slows down in to a 14% of its full speed .The diesel mixed gas is

injected and an electric spark is given to start the burning process. Then cranking motor is speed up

into 60% of GTs full speed, then control the fuel to bring up the turbine speed into 5100rpm so the

speed of the turbine is reduced through gear box to connect to generator. After the magnitude of the

voltage is varied by changing the excitation the frequency and the phase shift is matched through the

Synchroscope. When all these three conditions fulfilled the breaker is closed.

2.2.4 Spugaskanda Power Plant

2.2.4.1 Overview of the Plant

Sapugaskanda Power Station produces electricity which unit cost is the lowest thermal generation cost

compared to plants belong CEB. All are reciprocating cargo engine, these types of engines normally

produce large acoustic pollution and vibration this is due to reciprocating mechanism. Even though

maintains are heavily required, this plant does the lowest cost thermal electricity power generation.


Sapugaskanda Power Station

SECTION A4x20MW (installed capacity)

SEMT Pielstick-FranceV-type engine each having

18 cylindersCommissioned in1984

4x16 (currently running capacity)

SECTION B

Section B14x10 MW (installed capacity)

MAN & B&W - GermanyInline-type engine each having



Section B14x10 MW (installed capacity)

MAN & B&W - GermanyInline-type engine each having



Refinery

Treated oil

Storage Fuel Oil Centrifuge

Fuel treatment house

Fuel module

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Figure 2.22– Sapugaskanda Power Station Engine Arrangement

Total installed capacity is 160 MW. But currently these engines are not possible to run on that amount

of full load due to reducing their capabilities this is called derating of system of generation.

Thermal problems (reducing the efficiency of the cooling system)

Reduce the efficiency of engine

Generator winding efficiency reduce

This type of reasons cause to decrease the capacities of generation units

For the Electricity generation process, there are large no of other systems are also contribute in many

ways. Specially Fuel oil system, Lube oil system, cooling water system, fire protection system, steam

or hot water system, engine modules, generators, control panel systems, Transformers, switch yard

etc.. These are called auxiliary system.

2.2.4.2 Fuel oil System


Atmospheric air inlet

Air lesser heat and pressure

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Figure 2.23– Fuel oil System

The engines started by diesel and continuous running with Lanka Heavy Furnace Oil (HFO). To avoid

freezing the HFO the fuel lines are coupled with Heat tracking line (hot water line). Both lines are

covered with glass wool insulation. Air to fuel ratio is 14.1: 1 and free air is compressed by turbo

charger. Then charged air is cold to raise the density of air in order to insert more air mass into the

cylinder. Then charged air temperature is about 550C and after the compression stroke of the engine

the temperature of the compressed air is about 5000C.

2.2.4.3 Engine modules

There are two types of engines are in section A and section B as shown in Figure of Engine

arrangement these are cargo type heavy engines therefore at the starting of engines compressed air

should be injected in to the cylinder according to a sequence and drive the engine before combustion

process until come to speed which suitable for combustion (before diesel inject). Four strokes this

engines should be maintain, not only engine modules all the subsystems are maintain and test

according to a plan after taking outages.

Turbo charging is concept available in engine to increase the efficiency of the combustion process and

then overall efficiency.

2.2.4.4 Turbo Charger

Exhaust out of the engine emit large amount of heat energy, using this energy a turbine is driven and

the axis of that turbine is coupled to a compressor to pressurize inlet air supply to combustion process

this will increase the efficiency of the engine.


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Figure 2.24 – Turbo charger system

2.2.4.4 Generator

In section A all generation module consists generators are salient pole 14 poles machine, their

excitation current is supplied with the pole mounted PMG (Permanent Magnet DC Generator)

excitation level is controlled by AVR to stabilized required voltage output.

In section B all generation module consists generators are also salient pole14 poles machine, their

excitation current is supplied self exciter. Its operation is as follows, inside the generator having 5-

phase auxiliary winding, due to residual current in windings a current induces in that auxiliary

winding. That current is rectified through rectifier system and control through AVR and energizer the

exciter winding in exciter stator winding. Exciter rotor produces 3-phase current and this current is

rectified through rotating rectifier system and finally that DC current energized the generator

excitation level and now it is possible to control the excitation level from AVR.


5-phase

feed back fromterminal voltage

5-phase diode rectifier system

Exciter stator

Rotatingrectifier in therotar

AVR

Exciter rotor

5-phase auxiliarywinding

Rotor ofGenerator

StatorWinding

Stator ofGenerator

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Figure 2.25 – Self Exciter

2.2.4.5 Switch yard of the Power plant

Generation voltage is 11 kV and stepped up to 132kV by 5×50MVA transformers. Generated power is

transferred to Biyagama grid substation by using a double circuit lines.

2.2.4.6 Maintains

As mention in early this type of engine required heavy maintains in very efficient manner to manage

the plant for next future years, minimize the efficiency reducing and reduce the unplanned outage of

machines. Not only for this plant normally any plant should have the following maintain procedures to

achieve the above mentioned goals.

Conditional Maintains

Preventive Maintains

Routine Maintains

Breakdown Maintains

Preventive and Routine maintains are scheduled maintains monthly, daily or according to running

time. Conditional maintain is using measurements and check up determined required maintain before


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breakdown. Even the machines are maintained carefully there may be some break downs at that kind

of breakdown maintains are called breakdown maintains.

2.2.5 System Control Centre

System control centre is the place where is controlling the whole Sri Lankan Electricity Transmission

line including Power plants and Grid substations. According to the electricity demand System control

centre command power plants to connect the system or dispatch the plant from the system. Always

monitor the system frequency, system voltage, amount of Active power and reactive power, and

condition of main breakers. This center communicates with all plants and Grid Substations especially

with frequency controlling machine to keep the system stability.

2.2.5.1 System Stability Limits

System frequency should be 50 Hz ±1% and main system voltages should be as follows

Table 2.2 – System stability limits

System Voltages Required Voltage Limitations

220 kV Between +5% to -5% error range

132kV Between +10% to -10% error range

33kV Between +2% to -2% error range

System control centre control only 220kV and 132kV net work only.

If the demand active power is greater than the generation power, frequency decreases and vice versa.

There system control operators orders power station to increase their active power feed to the system

when the voltage drops they adds reactive power to the system.

Kothmale, Laxapana and Samanalawewa operate as frequency control centre of Sri Lankan power

system. Hydro plants are taken as frequency control due to the less responding time and more

controllability. Frequency control plant normally operates at half lord of its capacity. Droops setting at

the power plant is changed to frequency control mood


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2.2.5.2 System Operation

System operation means the controlling process of whole power system by communicating with all

plants and Grid Substations. This is the task should done by the operation Engineer of the system

control centre. Plant connection and dispatching is not a random task. It is done according to a

planning process.

2.2.5.3 Operation Planning

According to the load curve, to satisfy the demand generation should be planned by considering losses

also. For maintain of plant, grid substation or Transmission line outage planning should decide in the

systematical way to minimize to disturbances to the system.

Choosing of thermal power plants is depends on start/stop cost and unit cost of the thermal plants. But

decisions relevant hydro power plants are more complex. The main hydro power complexes are

Mahawelli and Laxapana hydro power complexes. So the raining pattern of the year must be

considered in order to select the more suitable complex. The Laxapana complex is totally owned to

CEB and can be use the water in the complex at any time. But Mahawelli complex is not only for

power generation. Priority of the usage in Mahawelli complex is as follows.

Drinking water

Environmental

Irrigation

Power generation

So the operation of the power plants of Mahawelli complex should follow the plans got by water

management meeting. The water levels of the reservoirs and ponds and cascading arrangement of the

ponds are also considered by the system control engineer in order to select the running power plant.

There is a parameter called water value depends on water level which is affecting to the power plant

selection.

Normally system control Engineers works with historical data and with their past experience.

According to the predicted demand curve they inform power station to connect, remove, increase and


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decrease their power. For that they make daily dispatch schedule and send them to the relevant power

stations individually.

2.2.5.4 Under Frequency Load Shedding

Under Frequency Load shading concept is important if suddenly large load connected to system or if a

plant trip off due to fault. Then that system becomes unstable at such moment frequency controlling

machine also may not possible to bear the impact. Frequency is decreasing rapidly this may cause

cascade tripping of generators and may cause total black out, system can regain the stability by

reducing loads from the system. Feeders should cut off automatically to reduce the load. According to

following table feeders are cutoff by breakers.

Table 2.3 – Under frequency load shading schedule

Frequency (Hz) Schedule of Load cut out

48.75 05% of the load cut out from the system





2.2.6 CEB Head office Generation and Transmission Planning division

Generation and transmission planning is very important to generate and transmit sufficient amount of

electricity to satisfy the consumer demand according to the growth demand (National Power and

Energy demand forecast). CEB is the authorized institute in our country to develop and maintain an

efficiently coordinated economical electricity supply system for the country. According to CEB plans

its generation, Transmission and distribution expansions in order to provide reliable quality electricity

to entire country at affordable price.


Training Report_______________________________________________________________________________________________________________

2.2.6.1 Planning and Demand forecasting

First step of planning process is forecasting the future electricity demand for upcoming 20 years by

investigating 10 years past data and considering the forecasting models this is called National Power

and Energy Demand Forecast. There are two methods,

Time trend method

Econometric methods

CEB generation planning unit uses econometric method. For the forecasting it is required variable like

population, GDP Average Electricity demand, Electricity price etc. The forecast is done by

considering following 3 major categories of consumers.

Domestic

Industrial ,General Purpose and Hotel

Street lighting and religious


Capacity enhancements and transmission expansion proposals

System studiesGeneration expansion plan

Satisfactory

Figure 2.26 - Transmission planning process

Long term transmission expansion plan

Generation expansion plan

NoYes

National power and energy demand forecast

Grid wise demand forecastDistribution development plan

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2.2.6.2 Generation Planning

Generation planning should be prepared in order to fulfill the above forecasted electricity demand by

considering National Power and Energy Demand Forecasting, recommendations and environmental

factors are also taken in to consideration. This planning is called the Long Term Generation Expansion


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Plan (LTGEP). In the case of demand forecast they are using software called WASP-iV. The inputs

and outputs to the software are as follows.

Figure 2.27 – WASP-iV Software

Even simply sketched the generation planning using WASP-iV as above, it is not an easy task due to

that software not being user friendly. Output of the generation planning is the very best suitable model

software is doing complex calculations and estimations.

2.2.6.3 Transmission Planning

Transmission planning is required to ensure the reliability of transmission network to match with load

growth and future generation hence estimate the investment required to implement transmission

developments. As mention above the objectives of transmission planning are,

Ensure reliable and stable power system

Estimating the investment

In order to above objectives on transmission network system, they are preparing a Long Term

Transmission Expansion Plan. The key inputs are National Power & Energy Demand Forecast, Long

Term Generation Expansion Plan and Regional medium voltage plan (distribution regions). Load flow

analysis is done to identify the satiability of the system at each year according to the previous

planning.

2.2.6.4 The load flow analysis

Load flow analysis is done using software called PSS/E. They model whole the network including all

the grid substations (Load bus), Power Stations (Generator bus) and one Power Station called Slack

bus which is balancing the equation,

Generation = Load + Losses


Training Report_______________________________________________________________________________________________________________

At the transmission planning following planning criteria are considered in load flow analysis

Thermal maximum Night peak

Thermal maximum day peak

Hydro maximum Night peak

Hydro maximum day peak


Tx line

Line losse

Generators

Switch yards

loads

Isolater or Breakersswitch gears

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In following manner model whole the network including all the considerable loses loads and sources

Figure 2.28 – Model in PSS

By identifying required upgrading next step of the Transmission planning is finding of the financial

facilities to carry out the required updating.

2.2.7 Rathmalana and Pannipitiya Grid Sub Station

Grid Substations are essential in any electrical transmission network to distribute through 33KV

feeders that process is done by this types of grid substations which are spread over the country and

connected to transmission system. The grid substation is converting 132 kV or 220 kV to 33 kV by

using step down transformers. But if 33 kV generations are available that power come through feeders

and step up in that step down transformer in reverse direction actually power flowing direction is not

possible to say exactly according to power requirement it flows.

2.2.7.1 Rathmalana Grid Sub Station

Rathmalana grid substation receives 132kV double circuit line from Pannipitiya and using 132/33kv,

31.5MVA three transformers step down the voltage to feed 9 feeders. Three of them are spare, there is

single bus bar for 132 kV and single bus bar 33kV normally two transformers are on load and other

one is the backup transformer

2.2.7.2 Pannipitiya Grid Sub Station


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33kV 12 feeders are feeding by this Pannipitiya grid substation double circuit 220 kV Biyagama line is

connected to 220 kV switch yard, 132 kV switch yard is connected to double circuit Rathmalana line,

Dehiwala 132 kV underground line, Horana 132 kV line Mathugama 132 kV line and to the 220 kV

yard through 220 kV/132 kV transformers these are single phase Auto transformers. Even there are

tertiary winding it is not in use present for any use full work. There is a capacitor bank in Pannipitiya

Grid substation it is also not working.

2.2.7.3 Components in substations

Basic components in substations are as follows,

Transformers (Main and auxiliary)

Breakers

Isolators

Current Transformer (CTs)

Potential Transformers (CVTs)

Bus bars

Feeders

Earthing mechanism

Protection system

Control panels

2.2.7.4 Power Transformer

Normally transformers are critical and expensive components in grid substation. Therefore protection

is essentially required to limits damages to transformers while the operating condition because high

cost and long outages if transformers failed. Failures of transformers are categorize as follows,

Winding failures

Core faults (core insulation failures)

Terminal failures

On load tap changer failures (mechanical, electrical, short circuit, over heat)

Abnormal operation condition (over fluxing, over load, over voltage)


Training Report_______________________________________________________________________________________________________________

Other external faults

2.2.7.5 Protection method of Power Transformer

Types of protection use in transformer to minimize damages due to above faults

Electrical protection (Over current protections, earth faults, Differential over excitation

protection)

Mechanical protection (Bucholz relay, pressure relief valve, pressure relays)

Thermal protection (Heating due to over exciting hot spot temperature)

2.2.7.5.1 Hot spot temperature

In design of transformer designer decides the hottest location in the winding, protection mechanism

can be used in this position to sense the temperature at this point and then alarming or tripping setting

is in used to protect from overheating the transformer.

2.2.7.5.2 Bucholz relay

Critical protection for large oil filed transformer with oil conservator. This gas and oil actuated relay is

protecting transformer against internal faults. It is two stage relay with first alarm and then at the

second stage trip the transformer.

2.2.7.6 On load tap changer

On load tap changer is necessary to maintain a constant voltage on LV terminal for varying load

conditions. This is achieved by providing taps generally in HV side due to lower current level in HV

side. Normally OLTC is a separately apart from the transformer tank it uses separate oil conservator.

No transformer oil are use together to mix the reason is OLTC when change taps make arc then the oil

filled in OLTC is always cause to rapid changes, therefore OLTC uses separate tank and separate oil

conservator. The difference of OLTC from No-load Tap changer is No-load tap changer cannot tap

changing at loaded time. (In power plant uses these no-load tap changers)


Training Report_______________________________________________________________________________________________________________

2.2.7.7 Dehydrate filter breather

To flow transformer oil from conservator to transformer tank, there should be a pressure in to

conservator this pressure supplied by filling air in to the conservator but moisture and dust particle

should be removed. So this in coming air through this dehydrate filter, to remove dust particle first

air comes through air medium and then to remove moisture air comes through silica gel medium.

2.2.7.8 Pressure relief Valve

In an internal fault if tripping is not occurred there may generate high pressure inside the transformer,

due to this high pressure inside the transformer it can be exploited. This will cause large disasters and

damages to other properties also. This is prevented by having week point on transformer tank wall this

is the pressure relief valve.

2.2.7.9 Switching in a switch yard

Grid substations have switching, protection and control equipment. Switching is an important function

performed by a substation. There are two events of switching which are,

Unplanned switching

Planned switching

For maintain purpose planed switching is done, inside the grid station or for outside maintains.

Unplanned switching events are occurring due to system disturbances, faults in equipments and hence

for protection. Switching functions are done in switch gears (isolator, breaker). Isolators are manually

or remotely at no load condition. Breakers are the special switching elements constructed to switch at

on load condition, these breakers are also having both remote and manual operation functions, and

they are quick response therefore, in system disturbances breakers are switching for protection

2.2.7.12 Circuit Breakers

This switching element has the switching ability at fault conditions and also at normal conditions.

Breakers are manually or remotely possible to be operated at normal condition. At the operation

condition due to high voltage and high current arc can produces, but due to switching doing in arc

quenching medium and possible disturbances and damages are prevented.


Terminals

Terminals Terminals

Insulator

Metalic contact

Rod activated bycharging mechanism

Compressed SF6 gass

Uper metelic contact

Lower metelic contactor

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Arc quenching mediums are,

Vacuum

Air

SF6

According to the voltage level quenching medium vary for breakers.

For the quick operation at system faults there is a charging mechanism to break the switch instantly.

Spring charged breaker

Pneumatic breaker

Hydraulic breaker

Due to stored energy in some means in above mechanisms at tripping condition suddenly relies the

contacts in SF6 medium.

Figure 2.29 – SF6 breaker


Terminals

Insulator Current transformer

Output from CT

To control pannel

Terminals

Insulator

Capacitor

To control pannel

Transformer

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2.2.7.13 Current Transformers

Figure 2.30 – Current Transformer (CT)

2.2.7.14 Potential Transformers

Figure 2.31 – Potential Transformer (CVT)


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2.3 Training Experience in Amithi Power Consultants (Pvt) Ltd

2.3.1Testing and Measurement

At the Amithi power consultants following tastings were performed.

Insulation Testing

Continuity Testing

Earth loop impedance

RCD functioning

Earth Resistance

2.3.1.1 Insulation Testing

Testing of insulation resistance is strongly required for assure the safety of personal, electrical

equipment and other properties, normally this test is done on

Cables

Motor and Generators

Single phase and 3-phase Transformers etc


Very high sensitive Ammeter Very high Voltage source

Megger testerTerminals

NE

L1 L2 L3

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Comparing with standard insulation level for electrical systems, we can recommend the systems if the

insulation level is greater than the standard levels.

Megger meter is the testing equipment used to measure the insulation resistance value.Normally

insulation level should be mega Ohm values under testing. To measure suchvery high value resistance

equipment uses very large DC voltage and then possible to measure considerable (measureable)

amount low current constant voltage source is applied to the resistance to be measured and the

resulting current is read on a highly sensitive ammeter circuit as shown in figure.

Figure 2.32 – Internal arrangement of

Megger tester

Digital meters are calibrates to measure the

resistance directly because injective voltage sources is known.

2.3.1.2 Cable Insulation Testing

Testing insulation level of cables in domestic industrial is recommended for safety and as preventive

maintains of cables especially in industrial electrical systems it is more required. For testing insulation

between cables other end of cable should be cut out the connections from breakers.


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Figure 2.33– Testing insulation levels of cables

Likewise all combinations are measured and note down as below (result of a test in Elakanda fishery

Harbor)

Table 2.4 – Cable insulation levels

L1 - L2 L1 - L3 L1- N L1- E L2 -L3 L2 - N L2 - E L3 - N L3 - N N- E

DB1 to

SDB1

63A

MCB263 440 197 165 272 270 16 2 93 145

Normally LV cables should have insulation level greater than 1MΩ but abnormal deviations are also

taken in to consideration and inform to recheck the cable insulation layer damages.

Following Voltage limits are apply for that specific voltage level for insulation testing

Table 2.5 – specific voltage level for insulation testing

Equipment or Cable Rating(V) DC test Voltage(V)

24 to 50 100

50 to 100 250

100 to 240 500

240 to 550 1000

2400 2500

4100 5000

Below is shown the Megger tester with details that we used in cable testing.

Digital Insulation Tester

Insulation resistance: AC voltage and conductor resistance

measurement

Insulation test mode: Comparator, memory, auto-hold and

discharge function


RCD

RCD tripping signal

auxilary supply input

load side

CT

auxilary supply input

CT signal input

Take RCD tripping signal to ourOmicron device

Make Current loop through CT

Omicron device

Breaker

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All test modes: Live-line alarm (Exchange AC voltage measurement)

Easy to view, function-free display

Figure 2.34 Digital Insulation Tester

2.3.2.3Relay testing

For the relay testing Omicron secondary injection kit was used. As shown in below, this equipment

contains more good advantages.

Omicron Testing kit (Omicron CMC-256-6 - Relay Test Set)

OMICRON secondary injection test sets and measurement devices is more popular in Electrical

Industry, Railway as well as for Relay and Measurement Device Manufacturers due to having

following features. It is,

Portable

Reliable operation

Accurate measurement

Possible to connect to any PC which having a serial port

2.3.2.3.1 Secondary injection and Primary injection test on relays

Secondary injection and Primary injection tests are normally conducted to check the operation of the

breaker and other protective relay devices. In primary injection test relatively high current is applied to

the primary side. This is done to prove that current transformers and protective devices are all properly

connected.Secondary injection test is normally conducted by applying relatively small current in

secondary side and therefore possible to check the correct operation of relays devices

2.3.2.3.1.1 Secondary Injection test on relay

As shown in figure connect the test device probes across RCD tripping signal output which is

connected to the breaker for tripping if fault current occurs. To make a fault current put a wire through

CT and connect it to current output of OMICRON device. And connect the Personal computer through

the serial port which has installed the software. Then increase the given loop current and measure until

trip off using PC measure the tripping current. And consider setting current and apply that until


Training Report_______________________________________________________________________________________________________________

tripping and if current vales and time delays are not suitable. Set current and do the test until the

recommended level observe.

Figure 2.35_Secondary Injection test on relay

2.3.3 Capacitor Bank Designing

Industrial tariff is charged for maximum demand also reason is when Consumer uses reactive power

supply authority have to generate reactive power, the larger current draws. Therefore industrial

Electricity bills are very high. Not being that reactive power consumes in loads this power supplied

using Capacitor bank.

Applicable Standard

IEC 61000-3-6

2.3.3.1 Energy survey Results

As per The Energy Survey a Power Analyzer (Data Logger) was fixed for One day Time Period of full

working hours (06:10:00 - 15:40:00) and followings are the Collected Data after analyzed.

The Average values of each phase is as follows at the measuring stage

Table 2.6 – Energy survey result summeryKularat hnaM . P .D .S .C .44

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Phases Maximum

Current

Maximum KW Maximum KVar Maximum KVA Maximum

KVA

Red phase 1605.75 242.879 277.307 370.733 370.733

Yellow phase 1750.67 28.699 288.816 406.175 406.175

Blue phase 1720.24 257.901 304.1 401.81 401.81

Figure 2.36_ Measured Active power and Reactive Power Apparent power against Time

Above figures shows the variations of measured data (about power) against time and we can have a

good idea about the reactive power variation.


6:10:00 6:55:00 7:40:00 8:25:00 9:09:59 9:54:59 10:39:59 11:24:59 12:09:59 12:59:59 13:50:00 14:35:00 15:20:000

200

400

600

800

1000

1200

1400

Avg. KWAvg. KVAAvg. KVAR

6:10:00 6:55:00 7:40:00 8:25:00 9:09:59 9:54:59 10:39:5911:24:5912:09:5912:59:5913:50:0014:35:0015:20:000

200

400

600

800

1000

1200

1400

1600

1800

2000

1Avg. Amp2Avg. Amp3Avg. Amp

767.097 KVA767.097 KVA

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Figure 2.37_ Measured each phase currents against Time

Above figures shows the variations of measured data of phase currents against time and by carefully

observing we can have a good idea about unbalances of the phase.

2.3.3.2 Recommendations

Installation of capacitor Bank

It is recommended to install a Capacitor Bank to Improve the Power factor (power factor correction)

and then the Demand will get lower than 1171.659KVA.

2.3.3.3 Calculation and the Size of the Capacitor bank

Figure 2.38 – Phaser diagram before and after install the capacitor bank

S1=√P12+Q 12

S2=√P22+Q22

cos∅ 1= P1S1

cos∅ 2= P2S 2

∆Q=Q1−Q 2

Table 2.7 – System variable before and after capacitor bank installation


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Description Before Installation of Capacitor Bank After Installation of Capacitor Bank

Average Demand at maximum

reactive powerS1=1171.659KVA S2=767.57 KVA

Power at maximum Reactive

powerP1=765.946 KW P2=765.946 KW

Reactive power at maximum

Reactive powerQ 1=870.225 KVar Q 2=50 KVar

Power factor angle at

maximum Reactive powerco s∅ 1=0.6537 cos∅ 2=0.99788

Power factor at maximum

Reactive power∅ 1=49.18 ∅ 2=3.7348

Here we assume that capacity of each capacitor is 50KVar (25KVar two capacitors connected in

parallel) therefore KVar tolerance can be consider as 50KVar

According to the Calculation size of the

Capacitor bank to be installed ¿820.225 KVar

Monthly Average Saving of Demand ¿ S2−S1=1171.659−767.57

¿404.089 KVA

Current Reduction by installing capacitor bank ¿404.089230×3

¿585.636 A

2.3.3.4 Phase balancing

It is recommended to balance the phase circuits to proper phase balance


6:10:00 7:00:00 7:50:00 8:40:00 9:29:59 10:19:59 11:09:59 11:59:59 12:49:59 13:50:00 14:40:00 15:30:000

200

400

600

800

1000

1200

1400

1600

1800

2000

1Avg. Amp

2Avg. Amp

3Avg. Amp

RYB RYB

2x25KVar Capacitor 50KVar Capacitor

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Figure 2.39 – Measured each phase currents against Time

Above figures shows the variations of measured data of phase currents against time and by inspection

it is clear that the red phase is mostly made up of low current. Therefore it is can be made up by

changing few load circuits of phases.

Therefore it is recommended to conduct a Proper Phase balancing system for Sub distribution boards

to stabilize the currents in each phase and it will compensate over current tripping of the breaker.

To get 50KVar capacitors 25KVar capacitors are parallel connected. Therefore the minimum

capacitance 50KVar the and tolerance is 50KVar.Accordingly there are 17 steps of connecting stages

of capacitors Following figure shows the internal capacitor arrangement of 50KVar three phase

capacitor

Figure 2.40 – Capacitor

According to load variation contactors are actuated using PLC. According to the analysis Capacitor

bank should be with Capacitors of 850kVAR in 17 Steps (35 No’s of 25kVAR Capacitors). The

Capacitor bank to include multiple steps and to be engaged automatically depending on the power

factor (reactive power).

2.3.4 Lightning Protection System Designing

Protection of against lightning is consider in following two ways


6:10:00 7:00:00 7:50:00 8:40:00 9:29:59 10:19:59 11:09:59 11:59:59 12:49:59 13:50:00 14:40:00 15:30:000

200

400

600

800

1000

1200

1400

1600

1800

2000

1Avg. Amp

2Avg. Amp

3Avg. Amp

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2.3.4.1 Direct lightning

Due to making low resistance path through structures there is a possibility of directly lightning strikes

on the building structure phenomena is called the direct lightning. In this design I have consider the

protection system design for direct lightning

2.3.4.2 Indirect lightning

Lightning on supply cable due to capacitive coupling and magnetic induction and that surge, lightning

effects coming indirect way, this phenomenon is the indirect lightning. For the protection from indirect

lightning, surge arrestors or surge diverters can be installed

2.3.4.3 Protection of structures against lightning

This design is to provide the protection for structures against direct lightning strikes. IEC 61024 and

IEC 61662 standards give the standards procedure to follow while design a Light protection system.

Table 2.8 – Standards for lightning protection design

IEC 61024-1 Protection of structures against lightning

General principals

IEC 61024 -1-1 Protection of structures against lightning

Part 1: General principles – Section 1 Guide A

Selection of protection Levels for lightning protection systems

IEC 61024 -1-2 Protection of structures against lightning

Part 1-2: General principles – Guide B

Design, installation, maintenance and inspection of lightning protection systems

IEC 61662 Assessment of risk damage due to lightning


Is

Start design

Collect dataStructure dimension and position

Environmental FactorsGround Flash Density (g)

Class of structure (Protection Level)

Calculate followingsCollection Area ()

Tolerable lightning Frequency ()Lightning strike frequency ()

Calculate Efficiency

Design a Lightning protection systemEfficiency

NOLightning protection system is not required

According to protection class (level)Select suitable Air termination methods

Training Report_______________________________________________________________________________________________________________

2.3.4.4 Risk Level assessment for the building

For every structure considered by the designer of the LPS protection shall decide whether or not an

LPS is needed. If it is designer should select a proper level of protection.


Model- 2Equivalent collection area for a structure where a prominent part encompasses all portions of the lower part of the structure

Model- IRectangular block

Model- 3Equivalent collection area for a structure where a prominent part encompasses all portions of the lower part of the structure

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Figure 2.41 – Selection of lightning protection system

Risk Level assessment Calculation

Number of ground flashes (Ground Flash Density)

N g=0.04×Tc1.25 per km2 per year

Where Ng = no of ground flashes per km2 per year

Tc = isokeraunic level(should be taken from isokeraunic map)

Number ofLightning strike frequency (Nd)

Nd=N g× A e×10−6 per year

Where Nd = direct lightning strokes on to a structure per year [Lightning strike frequency]

Ng = annual average ground flash density

Ae = equivalent collection area of a structure (m2)

Collection area ( Ae ) Calculation


Air terminationProtected Area

Structure to be protected

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Figure 2.42– Calculation of collection area

Tolerable lightning Frequency Nc

N c= 5.5×10−3

(C 1×C 2×C3×C 4×C 5)

C1 =Environmental Coefficient

C2 =Structural coefficient

C3=Structure Occupancy

C4=Structure Contents

C5=Lightning Consequences

(Values of each coefficient are given in ANNEX)

2.3.4.5 Methods of Air Termination System as per IEC

Protective Angle method

The protective angle method is suitable for simple structure or for small parts of bigger structures.

This method is not suitable for structures higher than the radius of the rolling sphere relevant to the

selected protection level.

Figure 2.43– Protective angle method

Rolling Sphere Method


Air terminationProtected Area

Unprotected Area

Structure to be protected

R

Front view Plan view

Training Report_______________________________________________________________________________________________________________

Rolling Sphere Method is suitable for complex shaped structures

Figure 2.44– Rolling sphere method

By considering unprotected area we have to re design by inserting extra air termination system or by

changing the positions of present system.

Mesh Size Method

The Mesh method is for general purpose and it is particularly suitable for the protection of plane

surfaces

2.3.4.6 Main Components of lightning protection system

Air terminals

Use air terminals in the form of vertical air rods for the protection of prominent roof top features or

equipment. Use strike pads to expose concealed conductors

Air terminal bases

The air termination network is the point of connection for a lightning strike. It typically consists of a

meshed conductor arrangement covering the roof of the structure.

Conductors

The down conductor system is the means of carrying the current of a lightning strike safely to the earth

termination network.

Conductor fixings


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Select the correct system of fixings for each part of the conductor system. Fixings are available for a

wide range of modern construction materials, stone, plastic and metal.

Conductor jointing clamps

Select a component for the interconnection of multiple conductors or for changes of direction. Jointing

clamps will ensure a low resistance, corrosion resistant connection.

Test clamps

In order to allow periodic disconnection and testing of the earth termination network, select a test

clamp to be placed within the run of each down conductor.

Earth electrodes

Choose an earth electrode to suit the ground conditions in the locality of the structure. Electrodes are

available in the form of rods and plates (lattice or solid).

Earth rod clamps

Select a high copper content alloy earth rod clamp for the connection of the earthing conductor to the

earth rod. In this below ground application, the clamp must ensure a good electrical contact and resist

corrosion throughout the lifetime of

Earth inspection chambers

Select an earth inspection chamber to protect the earth electrode connections. High strength chambers

are available in plastic and concrete

Bonds

Bonding is the most commonly employed method of avoiding the damaging effects of side flashing.

All continuous metalwork should be considered for bonding. All metallic services, eg:- cable

armoring, gas, water or steam piping, entering the building should also be bonded as directly as

possible to the earth termination network.


Training Report_______________________________________________________________________________________________________________

2.3.5 Thermal Imaging

2.3.5.1 Concept of Thermal Imaging

Temperature and electricity, there is a relationship between each other if any system uses Electricity

normally temperature of the system is rising. What if a high current flows in the system? the

temperature rises largely. Same as above scenario in many cases of faulty electrical systems get heat.

This temperature system temperature rises. Thermography is the process where calibrated thermal

imaging equipment is used to image and measure the temperature of various objects and according to

emission Infrared levels. Images are analyzed using computer in software to find over heated points

one in following manner, predicts the status of the current carrying objects, moving objects, and

thermal transfer barriers etc. Actually not only for electrical system observation but also various type

of thermal analysis this imaging possible to be used.

Figure 2.45– Distribution T/F in firing Figure 2.46– Power T/F firing

To prevent these sorts of disasters thermal Imaging is an important part of predictive and preventive

maintenance.


Training Report_______________________________________________________________________________________________________________

2.3.5.2 Importance of thermal imaging

To prevent these sorts of disasters thermal Imaging is an important part of predictive and preventive

maintenance. It is an accurate, easy, save lots of money and valuable time. Factory environment

thermal imaging is recommended in once a year. This predictive maintenance system can avoid lots

of your unforeseen hazards and make the production continuous. Further energy conservation can

be perfect as the energy loss points can be identified. Similarly for power stations and the connected

lines to national grid can be checked to avoid unnecessary outages due to some component failure.

The failing components can be identified and replaced the same in a planned way. Further jumper

defects can be predicted silly of the line and get the replacement in a planned maintenance work.

The power supply authorities can avoid fires occurring on the authority connection point /meter point

which may be a frequent occurrence in some areas. All this ensures the increase in productivity and

reducing down time for repair/replacement and labor needed for that.

2.3.5.3 Suitable for Thermal imaging in

Transmission and distribution equipments

Power Generation Plants

Grid substations

Switch boards, switch gear, Relays, breakers and fuses

Capacitor banks

LV cables

Motor control centre

Induction motors /all types of motors, motor bearings and shafts

Air conditioning plants

Gas Pipes/Thermal Fluid pipes/

All the electrical, mechanical and civil installations etc.


Training Report_______________________________________________________________________________________________________________

Figure 2.43– Thermal Images of Electrical Systems

2.3.5.4 Thermal imaging in LV switch board and Cables

At the imaging time no need to remove the enclosures since the thermal camera has the capability to

detect IR through the cabinet to an extent. For fine details open cabinet images could be obtained. If

something inside is hotter it transfers the heat to the outer cover through IR and convection and spots

heat signatures on the cover.

Before the test, camera equipment should to be calibrated according to the ambient temperature,

relative humidity, and distance between camera and imaging component. After completing of test

these thermal images is analyzed using FLIR software in computer to find temperatures of any point of

the images. It is easily possible to identify abnormal temperature rises.

By comparing with standard temperature allowable in standards for any equipment the final decision

can be taken whether the equipment is failing or not and then decisions are made of faulty with the

experience of the analyzing engineer.

2.3.5.4 Consider the following analysis of thermal images

Average ambient temperature of the plant area at the imaging time period is 280C.

According to the IEC standards IEC60439-1, clause 7.3 table 2– Temperature-rise limits

Table 2.9 –Max allowable Temperatures for LV panels.

Apparatus Ambient Temperature Max allowable Temperature /(0C)


Sp3 33.4

Sp2 27.2Sp1 26.4

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Temperature/(0C)Rise/(0C)

Metal Plastic Metal Plastic

Conductors 28 - - 70

Conductor terminals 28 70 - 98 -

Operating parts 28 15 25 43 53

Enclosures 28 30 40 58 68

Consider following Thermal image of cable running in to a DB

Figure 2.48 –Thermal image of cable Figure 2.49 –Digital image of cable

Table 2.10 – Cable temperature Analysis in FLIR software

spot Temperature /(0C)Max allowable Temperature according to

the Standard/(0C)Location

Sp1 26.4 98 Refer digital image



Sp1 27.2

Sp5 35.9

Sp4 36.1

Sp3 43.2Sp2 37.3

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Sp3 33.4 98 Red Circled

Operating temperatures of the three cables points are below than the maximum allowable

operating temperature indicated in the standard. But it can be noted that the temperature of Sp3 is little

bit higher than Sp1 and Sp1 temperatures but that all cables are carrying equal currants. So it’s

obvious that, for the temperature increment of Sp3 is not due to carrying high currant. This

temperature rise is due to contact at the end of upper DB termination connection point may not contact

well or sometime contamination of dust particles around termination point might be the reason for this.

So it is recommended to check for the proper cable termination and clean the cable termination area

for dust.

Consider following Thermal image of cable running in to a DB

Figure 2.50 –Thermal image of LV breaker Figure 2.51 –Digital image of LV breaker

Table 2.11 – LV panel temperature Analysis in FLIR software.

spot Temperature /(0C)Max allowable Temperature in

Standard/(0C)Location



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Operating temperatures of the two cables and operating parts are below than the maximum allowable

operating temperature indicated in the standard. But it can be noted that the temperature of left side

breakers is little bit higher than compared to others those incoming cables are also having high

temperature. This temperature rise may due to higher current flowing through this breaker than other

breaker also at cable termination connections to breaker may loosen and they may not contact well. So

it is recommended to check for the proper cable termination.

2.3.6 Electrical installation design

Design of electrical installation should be done according to some standards. Normally BS7671 IEE

Regulation is used. According to the consumer requirement following procedure is follows to do

installation design.

Lighting, switches and Socket outlets

Pump, lift, AC like special equipments

DB layout

Load calculation cable selection

Single diagram

BOQ and specification preparing


L - Length of the RoomHm - Mounting Height of Fitting (from working plane)W - Width of the Room

UF = Utilization Factor

MF = Maintenance Factor

MF = Maintenance Factor

F = Total Flux (Lumens) from all the Lamps in one Fitting

E = Lux Level Required

Where N = Number of Fittings

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2.3.6.1 Lighting design And Switch placing

Lighting system design should be done by considering occupancy to keep required (enough) light, as a

designer should have a good idea about the civil structure of each room and its main tasks for that

designer should get detailed drawing of the building. Different places require different amount of Lux

levels for a proper functionality. According to consumer requirement designer should do the optimum

lighting design, for that normally there are standards light levels for different places.

2.3.6.1.1 Factors and procedure to consider while lighting design

Figure 2.52– Lighting design

2.3.6.1.2 Utilization factor

The Utilization Factor is the proportion of light flux emitted by the lamps which reaches the working

plane. For the calculation, I have taken it as 0.5

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2.3.6.1.3 Maintenance factor

Due to the dust and other issues, the initial lighting level decays over time. Therefore this factor

represents the room condition. For the calculations, I have taken Maintenance factor as 0.8

2.3.6.1.4 Suitable lighting and fittings

At the design cost minimization, architectural beauty and so many other factors are also taken into

consideration. Therefore suitable lighting and fitting should be selected also by considering Wattages

of bulbs. There are several types of lights are available such as incandescent, fluorescent, compact

fluorescent (CFL), mercury vapor bulbs and LED lights. But in our designs never used incandescent

bulb due to huge inefficiency

Above calculated number of luminaries are then placed on the AutoCAD drawing at this stage we

should consider the architectural beauty according to the occupancy of the place. After placing the

lights, the required switches for light operating should be placed by considering accessibility, ease of

use and interior beauty. Switches are also have different design according to the consumer requirement

select the switch at the switch placing consider that single circuit must not contain more than 10-12

lights.

2.3.6.2 Socket outlets and DB layout

Ease of accessibility, possible hazards and disturbances to interior beauty, by considering possible

equipments may use in the building, socket outlet and DB should be selected and placed. In

distribution board locating consider the distribution of the circuits

2.3.6.3 Load calculation

After finishing the lights, sockets and switches layout, a load calculation is done. The load calculation

differs from application to application.

As an example, for the shopping complex, the lighting diversity factor is taken as unity. In a house,

this can be taken as 0.6 to 0.8.according to application and the consumer type this thing have to be

decide by the designer. Also the sockets load is also taken considering the diversity factor.

2.3.6.4 Selecting Protection Devices

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By determining the loads for circuit wise, floor wise and DB wise etc we have to decide the total lights

and sockets load, plus any additional loads the protection devices are selected. The main breaker is

selected such that it is greater than the maximum load. To select that breaker, total load of each floor is

calculated. Then an MCB or MCCB is selected depending on the level of control needed. Also the

RCCB’s are selected considering the main breaker and depending on the earthing system used.

2.3.6.5 Cable Selection

Cable size should be selected that voltage drop at connection points of equipments not exceeding 4%

from at supply point. For the cost minimization minimum as possible cross sectional area of the cables

should be selected. By considering no of cores, insulation type, armoring application temperature,

cable laying method etc suitable cable detail should be selected as given in BS7671.

It is given in standards as follows,

I z> I b

1.45 I z>1.125 I n

I n> Ib

Where I z=current carryingcapacity of conductor withderating factor

I n=nominal current ofthe

currentdevice

I b=design current

All these conditions should be satisfied.

2.3.6.6 Single Line Diagram

Single line diagram is the diagram given the detailed and summarized diagram of each db and the

equipment inside the DBs protection devices. Conductor detail and all these are how to connect to

each other. This diagram gives the enough details for technician to decide the constructions.

2.3.6.7 Bill of Quantity (BOQ) and Specification report

BOQ is consist of each and every one of items should be used to construction each items cost of them,

labor and required function cost are available there. This is very important part of a project not only

for do quotation for the project but also for analyze the project cost and estimate the real value of the

profit of the project. it is not required to put the cost details in BOQ by the design engineer. Anyway

this includes the some short details about equipments and standards procedures.

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3. Conclusion

The University of Moratuwa Engineering Faculty, the Department of Electrical engineering and the

National Apprentice & Industrial Training Authority(NAITA) is doing a great job in arranging

industrial training to the engineering undergraduates in order to expose our a future in industry and

putting the base of the future carrier buildings.

I started my industrial training period on 28th February 2011 and since then I had my training for 25

weeks up to 02nd September 2011. This was my first working experience in any sort of company or

industry with exactly exposing to the Electrical Engineering field. I think I gathered knowledge and an

experiences which are very different from what I have learnt from the university and different from

each other in three different places. I am personally happy to be an undergraduate trainee in CEB,

LECO and APCL.

This training period was a great opportunity for me to get a real idea about the electrical industry. Now

I have taken that real idea about the working environment. I was in an academic environment at the

university therefore I hadn’t enough practical exposure at university such as in industry. But the

having that theoretical knowledge of electrical system always it make me easy to realize and

understand that practical work by compare both together, in such time some hypothetical theories.

Therefore it is an important part of the degree program and I recommend and appreciate this type of

training module.

As a very large organization in Sri Lanka I was very happy to say I got the chance to become an

undergraduate trainee in that organization. From my experience at CEB what I feel is that the

Engineers and other level of professionals did maximum as possible with wasting their valuable time

to give something for us even though we had no more chance to get hand on experiences in CEB. As a

suggestion I like to suggest that time period for one place at CEB should increase at least to two weeks

because we had allocated only single week for Kelanithissa power plant, Kelanithissa combined cycle Kularat hnaM . P .D .S .C .iv

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power plant and two GIS and switch yard. In such time we are not possible to get good experience at

each place. Anyway within that eight week in CEB we got the maximum as possible. Even I have

studied about Electrical machines, power generation and power transmission actual idea of what we

are learning at the university is got at the training and at most time comparing theories and practical

work carried out. So it was a great opportunity to me as a future my carrier in this Engineer field. By

involving different level of skilled and different level of professional in CEB we got great experiences.

In LECO as a trainee, I got many experiences about the power distribution functions. LECO is a well

organized company which is involving distribution functions in the country, as for undergraduate

electrical engineer useful training was provided by LECO in four week training period. In that four

week training period I got lot of experience and knowledge about many distribution equipments used,

distribution functions and procurements etc. Due to being in several training place different kind of

experiences were taken. Engineers and technicians helped in various ways to understanding of their

functions. Through LECO training I could get practical knowledge and experiences, Definitely this

knowledge and experiences will be more important in my future

In plant traineeship was scheduled in Amithi Power consultants (PVT) LTD within last 13 weeks. I

was able to get a real industrial exposure through this Amithi Power Consultants which is one of the

leading electrical design firm in Sri Lanka. Any low voltage and many high voltage designs and

consultants are handled. So many local and foreign projects have been designed and consulted by this

company. In such company I was able to get my third industrial training that it was a great opportunity

for me. Within this 13 weeks training period in the company I was able to gain lot of experiences. Day

by day I was able to learn something new about the electrical engineering. I had no idea at very

beginning about most of designs but according to procedure they followed to training I was able to get

the good knowledge about designing.

During my training period, I understood the nature of the role of an engineer at the work field. What

are the responsibilities for him, the position of an engineer at different managerial levels and how he

works with workers who belongs to upper and lower managerial. Before the training and at the

beginning I had no idea about the industry but now, after completing the training I feel the difference

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and how the theoretical knowledge apply in industry to perform in industry. Due to variety of training

place I got different experiences.

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Industrial Training Report

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