Electrical panel boards- Engineering training report

HIGHER NATIONAL DIPLOMA IN ENGINEERING

ADVANCED TECHNOLOGICAL INSTITUTE COLOMBO 15

 NAME

: G.K.T.PREMARATHN G.K.T.PREMARATHNA A

FIELD

: ELECTRICAL ENGINEERING (POWER)

PREFACE

Industrial training is an important experience in the learning procedure of an Engineering student which provides an opportunity to utilize the knowledge in a real working environment under the guidance of competent engineers.

Higher National Diploma in Engineering six months Industrial Training is coordinated by  National Apprentice and Industrial Training Authority (NAITA) in association with Industrial training division of the Higher National Diploma in Engineering in Advanced Technological Institute. I tried my best to keep to the guidelines stipulated by NAITA. This is succeeded by my own training experience, which is detailed to the most possible extent.

This report presents the experiences and knowledge I have gathered during the first 3 months th

th

training period starting from 10  February 2014 to 09  May 2014 at Orange Electric of OREL Corporation (Pvt) Limited. Chapter one reviews information about the training organization, its main functions, organizational structure, business products, welfare and safety practices. The experience and knowledge gained within the period of industrial training are presented in the second chapter. Information about the work shop I visited, duties and functions performed during the training  period is included. Problems encountered during training and solutions found are also discussed in the second chapter. In the third chapter, gives a conclusion of training and of this report.

2

Kasun Premarathna

Higher National Diploma in Engineering [HNDE]- Electrical 23-batch

ACKNOWLEDGEMENT I would like to offer my sincere gratitude to the Advanced Technological Institute (ATI) Colombo 15, National Apprentice and Industrial Training Authority (NAITA) and OREL Corporation (Pvt) Limited for offering this training opportunity.

Further I must extend my deepest gratitude to Mrs. Anodya Ariyarathna, Director of ATI Mattakkuliya. In addition, Mr. Yogaganeshan, Head of Department Electrical Engineering and all academic staff of my Institute who guides me at all the times.

I am grateful to Factory Manager of OREL Corporation (Pvt) Limited. for giving us this opportunity. I also appreciate the cooperation from Mr. Ekanayaka the training coordinator of Orange Electric. I would be grateful to thanks Production Manager Mr. Gervin Sugath, who gave

me the guidance for a better training. My special gratitude‟s also offered to all the Engineers and other officers. My sincere thanks also belong to Head of Department and supervisor in the Electrical department. Also I would like to thank all the other Electricians and Operators who helped me in many ways during this training period.

Above all the things, it is the efforts of my parents and the family members gave me strength and support. Finally I wish to convey my gratitude to everyone that I may have forgotten to mention above, who supported me to complete my In-plant Training successfully.

G.K.T.Premarathna, Student of HNDE, Department of Electrical Engineering, Advanced Technological Institute, Colombo 15.

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Kasun Premarathna

Higher National Diploma in Engineering [HNDE]- Electrical 23-batch

CONTENTS Title

Page

1.0. CHAPTER 01- INTRODUCTION

1.1. Introduction of OREL Corporation Private Limited  ..........................…........... 10 1.1.2. Vision ………………………………………… .…………………….… ... 11 1.1.3. Mission …………………………………………… .….…………………. 1 1 1.1.4. Businesses together with OREL Corporation ………….……….………. .11 1.1.5. Products Range of Orange Electric Factory ……………..…….………….12

…………………………………………………....….. 1 3 1.1.6. Quality Assurance …………………………………………………....….. 1.1.7. Organization ……………………………………… .…………………….. 1 3 1.1.8. Employee Facilities & welfare ………………………..…………………. 1 4

1.2. Safety Practices ……………………………………………………………...…... 15 2.0. CHAPTER 02 –  TRAINING  TRAINING EXPERIENCE

2.1. Orange Industrial Electrical workshop ………………………………………… 17 2.1.1. Panel assembling procedure ………………………………….………….. 18 2.1.2. Power circuit wiring procedure ………………………………….…….… 19 2.1.3. Control circuit wiring procedure ……………………………………..….. 19

2.2. Tools & Machines used in workshop …………………….……………..…….. 20 2.2.1. Basic tools …………………………………………………………… .…. 20

………………………………………………………… ……………………………… …… 21 2.2.2. Machineries ……………………………… 2.2.3. Nuts and bolts ………………………………………………… .…….….. 22 2.2.4. Panel accessories used in workshop ……………………………..……… 22

2.3. Electrical Protective Devises Used in the Panels ………………………......... 24 2.3.1. Fuses …………………………………………………………………….. 24 2.3.2. Miniature Circuit Breakers (MCB) ………………………………….…... 25 2.3.2.1. Standard dimensions of MCBs ………………………… ..……. 25

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Kasun Premarathna

Higher National Diploma in Engineering [HNDE]- Electrical 23-batch

2.3.2.2. MCB Distribution Box designing ……………………….…….. 26 2.3.3. Residual Current Circuit Breaker (RCCB) …………………………….... 26 2.3.4. Moulded case circuit breakers (MCCB) ……………………………….... 27 2.3.4.1. The Shunt trip coil and Under Voltage Tripping Coil ……..….. 29 2.3.4.2. Auxiliary contacts ……………………………………… ...…… 29 2.3.4.3. Installation process of MCCB internal accessories …………… 30 2.3.5. The Surge Protection Device ……………………………………….…… 31 2.3.6. Phase Failure Relay (PFR) ……………………………………………….  31 2.3.7. Overload Relay …………………………………………………….……. 32 2.3.8. Earth Leakage Relay (ELR) ……………………………………….…….. 32

………………………………………………… 33 2.3.9. Earth Fault Relay (EFR) ………………………………………………… 2.3.9.1. Characteristic settings procedure of Earth Leakage Relay ...….. 33

2.4. Measuring Devises Used in the Panels ………………………………… .….. 34 2.4.1. Current transformer ………………………………………………… ...…. 34

……………………………………… 35 2.4.2. Core Balance Current Transformer ……………………………………… 2.4.3. Indicator …………………………………………………………… ..……36 2.4.4. Ammeter ………………………………………………………… ..…….. 36 2.4.4.1. Connecting process an Ammeter ……………………………………… 36 2.4.5. Voltmeter ……………………………………………………… ..……….  37 2.4.6. KWh Meter (Energy meter) …………………………………..…………. 37 2.4.7. Digital Power Analyzer ……………………………………….…………. 37

2.5. Switching Devises Used in the Panels ………………………………………… 38 2.5.1. Relay …………………………………………………………………….. 38 2.5.2. Contactor ………………………………………………………………… 38 2.5.3. Timer Relay ………………………...……………………….………… 39

…………………………………………………… .………. 40 2.5.4. Push Buttons …………………………………………………… 2.5.5. Selector Switches …………………………………………… ...………… 40

2.6. Cables ………………………………………..…………………………………… 41 2.6.1. Cable Insulation Materials ……………………………………………….  41 2.6.2. Cable Lug ……………………………………………………… ..………. 41 2.6.3. Cable Numbering Tube ………………………………………..…………  42

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Kasun Premarathna

Higher National Diploma in Engineering [HNDE]- Electrical 23-batch

2.6.4. Current ratings of single core PVC insulated cable …………… ..………. 42

2.7. Bus bars ……………………………………………………………………..……. 43 2.7.1. Bus bar sizes and current capacity ……………………………… .……… 43

2.8. Distribution Panels ………………………………………...……………………. 44 2.8.1. Main Distribution Panel ………………...………………………..……… 44 2.8.2. Sub Distribution Panel ………………………………………… ...……… 44 2.8.3. The pump house distribution panel wiring procedure …………….…….. 45

2.9. Changeover Panels …………………………………………………………..….. 47 2.9.1. Manual Changeover Panel …………………………………...………….. 47 2.9.2. Automatic Changeover Panel (ATS panel) ………………………………  47 2.9.3. Automatic Changeover Panel wiring ………………………………...….. 48

2.10. Motor Control panels …………………………………………….…………… 50 2.10.1. Direct Online Starter (DOL) panel …………………………………….. 50 2.10.2 Cooling tower panel wiring …………………………………………….. 51 2.10.3. Star-Delta Starter panel ………………………………………………… 53 2.10.4. Fire pump panel wiring …………………………………...…………….  54

2.11. Power Factor Correction Capacitor Bank …………………………………… …………………………………… 57 57 2.11.1. Components Used in Capacitor Bank …………………….……………. 58 2.11.2. 6 steps Capacitor Bank Panel wiring …………………….……………. 59

2.12. Electrical Panel testing

…………………………………………….…….. .. 62

2.12.1. Testing equipment ……………………………………...………………. 62 2.12.2. Panel tests ………………………………………………… .……………  64 2.12.2.1. Visual inspection procedure…………………….…………….. 64 2.12.2.2. Insulation resistance testing procedure …………………..…. 65 2.12.2.3. Functional test ……………………………………..……….… 66

3.0. CHAPTER 03 - CONCLUSION

3.1. Conclusion ………………………………………………………..……… 67 3.2. Abbreviations

……………………….………………………………… ……………………….…………………………………… … 68

3.3. References ………………………………………….…...…………….…. 69 6

Kasun Premarathna

Higher National Diploma in Engineering [HNDE]- Electrical 23-batch

LIST OF FIGURES Figure 1.1

Orange Electric factory

10

Figure 1.1.4

OREL Corporation businesses

11

Figure 1.1.5

Orange Electric Logo

12

Figure 1.2.1

Electrical Safety Signs

15

Figure 2.1

Standard Panel Design

18

Figure 2.2.1

Tool box

20

Figure 2.2.1.1

Cable Cutter

20

Figure 2.2.1.2

Crimping Tool

20

Figure 2.2.2.1

Jig Saw

21

Figure 2.2.2.2

Electric Drill

21

Figure 2.2.2.3

Pneumatic Pop-Rivet Gun

21

Figure 2.2.2.4

Industrial Heater

21

Figure 2.2.3

Nuts and bolts

22

Figure 2.2.4.1

Din rails

23

Figure 2.2.4.2

Insulator mounts

23

Figure 2.2.4.3

Cable ducts

23

Figure 2.2.4.4

Wire End Caps

23

Figure 2.3.1

Cartridge Fuse

24

Figure 2.3.2

HRC Fuse with holder

24

Figure 2.3.2

MCBs

25

Figure 2.3.2.1

Standard dimensions of MCBs

25

Figure 2.3.2.2

MCB Distribution Box wiring diagram

26

Figure 2.3.3.1

Internal connection of RCCB

26

Figure 2.3.3.2

2 poles and 4 poles RCCB

27

Figure 2.3.4

MCCB and its auxiliary components

28

Figure 2.3.4

I - Thermal adjustment

28

Figure 2.3.4

II - Magnetic adjustment

28

Figure 2.3.4.2

Auxiliary contacts and Tripping Coil arrangement

29

Figure 2.3.4.3

Installation of MCCB internal accessories

30

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Kasun Premarathna

Higher National Diploma in Engineering [HNDE]- Electrical 23-batch

Figure 2.3.5.1

SPD device

31

Figure 2.3.5.2

wiring diagram of “OBO” SPD device

31

Figure 2.3.6

“ANLY” PFR and its connection diagram

31

Figure 2.3.7

“LS” Overload relay and symbol

32

Figure 2.3.8.2

“DELAB” ELR 

32

Figure 2.3.8.2

connection of ELR

32

Figure 2.3.9

“DELAB” EFR  and its connection

33

Figure 2.4.1.1

Types of CTs

34

Figure 2.4.1.2

Working principle of CT

34

Figure 2.4.1.3

CT connection

35

Figure 2.4.2

Core Balance Current Transformer

35

Figure 2.4.3

Connecting diagram of an Ammeter

36

Figure 2.4.4

Voltmeter and selector

37

Figure 2.5.1

Relay and relay base

38

Figure 2.5.2.1

“ABB” contactor

39

Figure 2.5.2.2

Auxiliary components

39

Figure 2.5.3.1

Timers

39

Figure 2.5.3.2

Analog timer internal connection

39

Figure 2.5.4

Push button and emergency button

40

Figure 2.6

PVC insulated cable

41

Figure 2.6.2

Cable Lugs

41

Figure 2.6.3

Cable Numbering Tube

42

Figure 2.7

Bus bars

43

Figure 2.8.1

Main Distribution panel

44

Figure 2.8.2

Sub Distribution panel

45

Figure 2.8.3

The pump house distribution panel wiring diagram

45

Figure 2.9.2

Automatic Changeover Panel

47

Figure 2.9.3

Automatic Changeover Panel control wiring diagram

48

Figure 2.10.1

Power circuit and control circuit of DOL panel

50

Figure 2.10.2.1

Power circuit of cooling tower panel

51

Figure 2.10.2.2

Control circuit of cooling tower panel

51

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Kasun Premarathna

Higher National Diploma in Engineering [HNDE]- Electrical 23-batch

Figure 2.10.3

Power circuit and Control circuit of star delta panel

53

Figure 2.10.4

Control circuit of Fire pump panel

55

Figure 2.10.4.1

Timer connection of fire pump panel

56

Figure 2.11

Power factor triangle

57

Figure 2.11.1

Capacitor Bank

57

Figure 2.11.1.1

Power capacitor

58

Figure 2.11.1.2

Capacitor switching contactors

58

Figure 2.11.1.2

Automatic power factor controller

58

Figure 2.11.2

Capacitor Bank power circuit drawing

60

Figure 2.11.3

Capacitor Bank control circuit drawing

61

Figure 2.12.1.1

Test Lamps

62

Figure 2.12.1.2

Clamp meter

62

Figure 2.12.1.3

Continuity tester

63

Figure 2.12.1.4

Megger tester tester

63

Figure 2.12.2.1

Visual inspection test report

64

Figure 2.12.2.2

Insulation Resistance test report

65

Figure 2.12.2.3

Functional tests reports

66

LIST OF TABLES Table 2.4.1

Metering Accuracy Classes of CTs

34

Table 2.6.4

Current ratings of single core PVC insulated cable

42

Table 2.7.1

Bus bar current capacity

43

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Kasun Premarathna

Higher National Diploma in Engineering [HNDE]- Electrical 23-batch

1.0. CHAPTER 01- INTRODUCTION 1.1. Introduction of OREL Corporation Private Limited Li mited

Figure 1.1- Orange Electric factory OREL Corporation Private Limited (Orange Electric Corporation) is the biggest electric company, which is manufacturing, exporting and importing world class Electrical Products based in Sri Lanka. With their customer oriented approach, all the business policies are based on high ethical values. They endeavor to maintain complete transparency in all the business procedures. All the 1000

employees of the company stand by the company‟s vision of attaining complete client satisfaction. They have earned the confidence of many eminent clients from countries like India, England, Australia, Austria, Maldives, Bangladesh, Pakistan, Singapore, Korea, Japan, Taiwan, Cypress, Nepal, Dubai, and Uganda. The Orange Electric was started in 1978. It started as an Australian Sri Lankan joint venture with Clipsal, with a simple assembly line producing a limited range of switches and sockets. From then on, the company experienced phenomenal growth and market leadership, manufacturing a complete range of electrical products. The sale of Clipsal Australia to the French multinational company Schneider Electric was a turning point in the history of the company, as this twist of fortune led to the foundation of Orange Electric. At this critical juncture it was decided to resist against the sale of the company to a multinational.

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Kasun Premarathna

Higher National Diploma in Engineering [HNDE]- Electrical 23-batch

Orange Electric was launched as the company‟s main brand in 2004. With the increase of their  product portfolio the company has five major factories in Maharagama, Boralesgamuwa, Ratmalana, Meegoda and Ranala. In these five factories they manufacture more than one million items for a month. Under the proficient headship of Mr. Kushan Kodituwakku, our respected MD, the Orange brand became an overnight success, securing market leadership within a short  period in the field of manufacturing, exporting and importing of Electrical Products.

1.1.2. Vision "To create a billion dollar global electrical brand"

1.1.3. Mission "To add more to life with electricity"

1.1.4. Businesses together with OREL Corporation OREL Corporation is converged 16 businesses

Figure 1.1.4 - OREL Corporation businesses b usinesses

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Kasun Premarathna

Higher National Diploma in Engineering [HNDE]- Electrical 23-batch

I was mainly involved with the

“Orange Electric” of “OREL Corporation‟ during the period of

industrial training, which is situated at Megoda, Padukka. This factory manufactures electrical components to the highest quality and most stringent international standards.

1.1.5. Products Range of Orange Electric Factory

Figure 1.1.5 - Orange Electric Logo



Low Voltage Switchgear

Low Voltage Switchgear which Designed for a flawless performance, the Low Voltage Switchgear available with us is largely used in varied industrial applications for providing isolation switching and earth leakage protection of electrical circuits. . 

Electrical Accessories

Electrical Accessories is assorted variety of Electrical Accessories includes Electrical Mounting Boxes, Electrical Plug Top, Electric Lamp Holder, and Electrical Ceiling Rose.. Designed to  perfection, the Electrical Accessories provided by them comply with the set industrial standards. standards.

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Bulbs

CFL Lamps are created a strong foothold in the business of manufacturing and exporting world class CFL Lamps. Tube lights and LEDs also produced in orange

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Cables

The Electrical Cables are specially manufactured using the best grade raw materials. Thus, these Electrical Cables are the best choice that is available in the markets all across the world. Moreover, the clients can access this enviable range of Electrical Cables in varied specifications that too at very reasonable rates.

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Kasun Premarathna

Higher National Diploma in Engineering [HNDE]- Electrical 23-batch



Industrial Electrical Application

They have made a mark in the field of manufacturing and exporting products for Industrial Application. These products are specially manufactured using premium grade raw materials and electronic components.

o

Power Distribution Panel

One of the major Manufacturers and Exporters is Power Distribution Panel. These Power Distribution Panels are trusted for Safety Reliability and Quality in LV Power Distribution. o

Steel Enclosure

The Steel Enclosures for Power Distribution Panels is fabricated using the finest grade raw materials.

1.1.6. Quality Assurance We are a quality oriented organization and so we make regular up gradations of the Electrical Products that are also inspected on varied parameters in compliance to our policies. Further, to add credibility to our name, we have been Awarded ISO-9002 in 1994 and ISO-9001 in 2000 for quality management system in the manufacture of electrical accessories. Also super brand status for the superior quality Electrical Products offered by us.

1.1.7. Organization Orange electrical is very highly organized company and It has very complicate organization system. The total number of employees at Orange electric is about 1000. This is main organization structure of orange electric.

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Kasun Premarathna

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Board of Directors



Chairmen



Managing Director

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Other Director



Factory Production Manager

Higher National Diploma in Engineering [HNDE]- Electrical 23-batch

1.1.8. Employee Facilities & welfare Employees Trust Fund (ETF) and Employees Provided Fund (EPF)



EPF is required Employee‟s contribution  is 8% of the total monthly earnings (To be deducted from the Employee‟s Salary) and Employer‟s contribution is minimum of 12% of the total salary of the employee monthly.

ETF is required Employee‟s contribution of 3% percentage of the earning of an employee. Working hours and Leaves



The normal working hours of the Orange Electric Factory are 7.30 am to 5.00 pm. Excess of normal working hours to be treated as overtime. The transport service is gone on according to the working times. An office employee shall be granted 14 days annual leave with pay in respect of the second and any subsequent year if he has been continuously in employment during the year.

Welfare



Orange Electric, a company who places great emphasis on the welfare of its employees has recently implemented

several distinctive programs, giving new meaning to „work life balance‟

whilst taking their „Healthy Employee‟ concept to an altogether higher plain. The Company has devised some interesting and special programs that greatly contribute.

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Kasun Premarathna

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Yoga and Karate sessions.

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Meditation programs and First Aid facility.

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Changing Room and Lockers.

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Meals, Tea & Washing facilities.

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Annual cricket match, New Year festival and ann ual trip.

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Bonus and Loans.

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Transport service.

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Welfare shop.

Higher National Diploma in Engineering [HNDE]- Electrical 23-batch

1.2. Safety Practices In the Orange Electric workshop, we used safety methods, because of electrocution is mainly due to serious injury. The operation of tools and machineries also cause to hazards. We considered about personal safety, human health and equipment safety. Below safety instructions were followed in workshop for the prevent from electrical hazards,

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Before installation, wiring, operation, maintenance and inspection of the panel, instructions or the catalogue were studied carefully to ensure proper o perations.

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We got the assistance from supervisor, before testing the experiment with electrical supply.

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Proper testing and checking instruments were used to find the live parts.

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We used only tools and equipment with non-conducting handles when working on electrical devices.

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We kept in mind to never handled electrical equipment when hands, feet, or when standing on a wet floor.

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We kept the workplace dry and free from oil, water and grease.

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The power source was disconnected before servicing or repairing electrical equipment.

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We kept in mind to use the equipment in a range of the rated voltage and current shown on the name plate.

Figure 1.2.1 - Electrical Safety Signs 15

Kasun Premarathna

Higher National Diploma in Engineering [HNDE]- Electrical 23-batch

Fallowing safety methods were  used to prevent from hazards while machinery works in workshop.

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We used personal protective equipment such as Safety shoes, Gloves, Ear Plugs, Mufflers, Safety Goggles and etc.

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Used appropriate tools and equipment for work.

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Before done the work, instruction was read properl y.

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We followed out to wear suitable cloth, not too tight and not too loose.

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After the work was finished, cleaned the surface and electrical switch off the machineries  power supply.

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We kept the floor of workplace free from oil, wat er and grease.

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Used cleaners for the clean the body.

The company has a response for all electrical work, systems and equipment under their control. They must ensure that and are given sufficient information of any known hazards or risks to health and safety to enable them to work safely; 

Suitable control measures are in place and followed.

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Installed suitable equipment for perform and the environment within which it will be expected to work.

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Equipments were calibrated correctly.

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Danger signs, Warning information and other safety procedures were presented in working place.

16

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First aid facilities and sick room was arranged in the compan y.

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Safety equipment and cleaners were provided in the workshop.

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Working areas were marked according to the proper standard.

Kasun Premarathna

Higher National Diploma in Engineering [HNDE]- Electrical 23-batch

2.0. CHAPTER 02  –  TRAINING  TRAINING EXPERIENCE 2.1. Orange Industrial Industrial Electrical workshop In Orange Industrial Electrical workshop, Power Electrical Panels were designed as per the IEC standards. These power electrical panels were trusted for Safety Reliability and Quality in Low Voltage Power Distribution. Power Electrical Panels made available in various specifications in Industrial Electrical workshop,

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Distribution panels o

Main distribution panels

o

Sub distribution panels

Changeover panels o

Manual Changeover Panels

o

Automatic Changeover Panels (ATS panel)

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Motor control panels



Capacitor Bank panels



Steel enclosures

The Power Electrical Panels consist of metering devices, protective devices, switching devices, conductors, bus bar chambers, indicators, circuit breakers, capacitors and many other types of equipment. Before designing electric panel the following details should be incorporated into it.

17

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Location and dimension of the panel

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Load description, Amperage, Voltage required

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Cable size and conduit size

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Type of insulation.

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Ventilation, temperature and space arrangement in the panel

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IEC regulation

Kasun Premarathna

Higher National Diploma in Engineering [HNDE]- Electrical 23-batch

Figure 2.1 –  Standard  Standard Panel Design I was able to practice the process of panel assembling and panel wiring in Orange Electric workshop.

2.1.1. Panel assembling procedure 

First of all, the panel box, cover plates, panel door, mounting plate and benches were selected according to the given drawing.

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Door arrangement was fixed by using Panel hinge according to general arrangement.

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The door Beading and panel key mount was attached to the door.

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The cover plate bracket was prepared by using drill machine, tap cutting tool, flat screw driver.

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Switch gear benches and din rails were arranged on the mounting plate according to drawing.

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Mark holes position to fix the benches, din rail bracket, profile using pencil and drilled all holes using drilling machine.

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Taped all holes using tap cutting tool.

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Din rails and benches were fixed by b y using flat screw.

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Arrange bus bars, bus bar insulators, neutral link, neutral bar, earth bar, earth link as general arrangement using bus bar bend machine.

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Kasun Premarathna

Higher National Diploma in Engineering [HNDE]- Electrical 23-batch

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Made the holes to fix bus bar insulators, earth link, and neutral link etc. on mounting  plate and all holes were taped.

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All items were fixed according to general arrangement u sing proper tools.

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The door arrangement of indicators and other equipments was prepared according to drawing by using drill machine and Jig saw.

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All electrical equipments were fixed in to the proper p lace and mounting plate was fixed in to the panel box.

2.1.2. Power circuit wiring procedure 

The cable ducts was cut in to suitable size and fixed in to the panel box.

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The relevant wire size was selected according to current rating chart.

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The cable length was defined and cut the wires using wire cutter.

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The Lug was fixed to the wires using lug cramping tool and End cap was fixed in to the cable according to phase colour.

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Wiring was done according to the wiring diagram, Allen key, Phillips and flat screw drive.

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Marked the tighten nut using permanent maker pen.

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Checked the wire connection, cable size and connection.

2.1.3. Control circuit wiring procedure 

Auto cable was used to wire the control circuit.

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The cable length was defined and cut the wire using side cutter, wire striper.

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Print the tube number using ferrule print machine.

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Lugs were fixed to cable using cramping tool.

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The control side was wired by including numbers, Phillips and flat screw drive were used.

19

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Wire combines between control side and power side.

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The control line was neatly arranged b y using spirals and cable ties.

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Checked the wires connection.

Kasun Premarathna

Higher National Diploma in Engineering [HNDE]- Electrical 23-batch

2.2. Tools & Machines used in workshop When I was assembling the panels in the workshop, Fallowing tools and machineries were used. Before I used these tools and machineries safety rules and operating instruction were fallowed correctly.

2.2.1. Basic tools 

Hammer

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Screwdriver (Slot-head)

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Phillips Screwdriver

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Pliers

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Hacksaw

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Allen Keys

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Side Cutter

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Wrench (Box-End Wrench, Socket Wrench, Pneumatic Wrench, Open-end Wrench)

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Measuring Tape

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Cable Cutters

Figure 2.2.1 - Tool box

Cable cutters are useful to cut cables. Gilbow cutter (heavy-duty cable cutters) cuts the large size cables & common bas bar.

Figure 2.2.1.1- Cable Cutter 

Crimping Tool

A crimping tool is a tool designed to crimp or connect a connector or lug to the end of a cable. To use this crimping tool, each wire is first placed into the correct position. The hydraulic crimping tool crimps high gauge wire easily with steady hydraulic power.

Figure 2.2.1.2- Crimping Tool

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Kasun Premarathna

Higher National Diploma in Engineering [HNDE]- Electrical 23-batch

2.2.2. Machineries 

Jig Saw

A Jig Saw is a useful in cutting cu tting shapes, curves and removing parts from the panels.

Figure 2.2.2.1 - Jig Saw 

Electric Drill

A Drill is a driving tool attachment, usually a drill bit.  bit.  It is used for drilling, tapping and  boring holes in various materials. Some electric drills drown with rechargeable with rechargeable batteries.

Figure 2.2.2.2 - Electric Drill 

Pneumatic Pop-Rivet Gun

A pneumatic pop rivet gun is designed to fix the rivet nuts together without too much effort from the person handling the gun. The pneumatic pop rivet gun used compressed air hoses.

Figure 2.2.2.3 - Pneumatic Pop-Rivet Gun 

Industrial Heater

Industrial Heater is used to plastic welding, bending, bus bar insulation and many other  purposes.

Figure 2.2.2.4 - Industrial Heater

21

Kasun Premarathna

Higher National Diploma in Engineering [HNDE]- Electrical 23-batch

2.2.3. Nuts and bolts The fallowing nuts and bolts were used for the panel assembling and connecting devices in to the  panel box by me.



 Nail



Screw



Flat washer



Spring washer



Bolt

(CSK Bolt - 4x10mm, 4x12mm, 5x10mm, 5x12mm, 5x16mm, 5x20mm) (PH Bolt - 5x35mm, 5x20mm, 4x10mm, 4x12mm) (Hex Bolt -



Allen Bolt



Self tapping bolt





8x30mm, 8x15mm, 6x8mm, 6‹12mm, 6‹15mm, 6‹20mm)

 Nuts Stud nuts

Figure 2.2.3 - Nuts and bolts

2.2.4. Panel accessories used in workshop

22



Panel plate



Beading



Panel hook



Cables ties



Panel holder





Panel hinge / Chrome hinge





Panel key

Kasun Premarathna

 Name plates & danger stickers Earth bar

Higher National Diploma in Engineering [HNDE]- Electrical 23-batch



Din rail

Din rail is a metal rail of a standard type widely used for mounting circuit breakers and industrial control equipment inside panel.

Figure 2.2.4.1 - Din rails



Insulator Mounts

Bus Bar Insulator mounts are used for connecting line and neutral bar with panel mounting  board and connecting bus bar with panel board.

Figure 2.2.4.2 - Insulator mounts



Cable Duct

Cable duct is wire and cable management product for routing and concealing electrical wiring in control panels. Available in many man y sizes

Figure 2.2.4.3 - Cable ducts 

Wire End Caps

The wire end caps are used for easily identified wire. These end caps can be obtained various colour according to electrical colour code.

Figure 2.2.4.4 - Wire End Caps 23

Kasun Premarathna

Higher National Diploma in Engineering [HNDE]- Electrical 23-batch

2.3. Electrical Protective Devises Used in the Panels The electrical panel was designed with protective devices. Protective devises were used for human protection, system protection and equipment protection. In Orange Electrical panels were consisted with various types of protective devises. I was able to get knowledge about using  purpose, working principle, connection and testing of these protective devices.

2.3.1. Fuses A fuse is a type of protection device in electrical applications. Fuses are designed to open circuits the filament when excessive currents are present due to overloads or faults and to prevent further damage to the system. Short circuit, system overload, other device failures, lightning, static electricity or system overload are some common results in b lown fuses.



Cartridge Fuse

In cartridge fuse the fuse wire is enclosed in a transparent glass tube or bulb, the whole unit is sealed off. In case the fuse blows, it is to be replaced by new one as the cartridge fuse can not be rewired due to its sealing. In cartridge type fuses have many other sub types as MCB type, screw type, etc.



HRC Fuse (High Rupturing Capacity Fuse)

HRC Fuse consists of highly heat resistant material (such as ceramic) body having metal-end caps, which is welded by silver current carrying element. HRC Fuse has high rupturing capacity. It has constant fusing characteristics and operates fast.

Figure 2.3.1 - Cartridge Fuse

24

Kasun Premarathna

Figure 2.3.2 - HRC Fuse with holder

Higher National Diploma in Engineering [HNDE]- Electrical 23-batch

2.3.2. Miniature Circuit Breakers (MCB) In electrical panels, MCB was used as the basic protective device. MCBs are designed to automatically protect against overloads and short circuits, preventing damage to cables and equipment. Trip characteristics normally can not adjustable. MCB has thermal-magnetic operation. Over current protection is got the system by the thermal trip unit of the breaker. Short circuit protection is got to system by Figure 2.3.2 - MCBs

the magnetic trip unit of the breaker.

The MCBs‟ are in

single pole, double pole, try pole and four pole types. Every circuit breaker has a voltage rating that designates the maximum voltage it can handle and a continuous current rating, which is the maximum continuous current carry without tripping. The value of the kA rating, determines how much current the circuit breaker can withstand under fault conditions. When we consider MCBs we can see various MCBs with different ampere ranges and internal situations (Tripping). MCBs are classified according to the ampere. Type B - operate 3-5 times rated current and suitable for lighting loads Type C - operate 5-10 times rated current and suitable for lighting and motor load s. Type D - operate 10-20 times rated current cu rrent and suitable for heavy units, welding weld ing plants 

My experience

2.3.2.1. Standard dimensions of MCBs 

I was able to measure the standard size (in mm) of the MCB and RCCB. It was very important for the panel designing and arranging the panel box.

Figure 2.3.2.1- Standard dimensions of MCBs 25

Kasun Premarathna

Higher National Diploma in Engineering [HNDE]- Electrical 23-batch

2.3.2.2. MCB Distribution Box designing I designed fallowing Distribution Boxes for the 300 houses in the housing apartment. This



was designed for single phase 30A house. I have been used 30A isolator switch, 30A RCCB, four MCBs of 10A and six MCBs of 6A



according to the requirement. All were Orange p roduction. 2

4mm CU/PVC insulated wire was used for the wiring and single phase common bus bar was



used to connect the MCBs.

Figure 2.3.2.2 - MCB Distribution Box wiring diagram

2.3.3. Residual Current Circuit Breaker (RCCB) The Residual Current Circuit breakers (RCCB or RCD) are the safest device to detect and trip against earth leakage currents, thus ensuring protection against electric shock caused by indirect contacts. These devices must be used in series with an MCB. RCCB Available in 2 Pole and 4 Pole for domestic and Industrial application 1. Electromagnet 2. Current transformer secondary winding 3. Transformer core 4. Test switch L - Live conductor

conductor N- Neutral conductor 26

Kasun Premarathna

Figure 2.3.3.1 - Internal connection of RCC B Higher National Diploma in Engineering [HNDE]- Electrical 23-batch

RCCB works on the principle that in an electrical circuit the incoming current is the same as out going current. RCCB incorporates a core balance. The primary winding lies in series with the supply mains and load. Secondary winding is connected to a very sensitive relay. During flow of leakage current in the circuit an imbalance is created in the circuit which gives rise to leakage flux in the core. This leakage flux generates an electrical signal that is sensed by the relay and it trips the Mechanism thereby disconnecting the supply. When pressing the TEST button 'T', a fault is simulated via the Test resistance & RCCB trips.

Figure 2.3.3.2 –  2  2 poles and 4 poles RCCB The RCCBs with a rated residual operating current (I∆n) of 30mA or less are used in place of more conventional RCCBs with higher residual operating current ratings. The Rated current range varied 10mA to 1A.

2.3.4. Moulded Case Circuit Breakers (MCCB) In every panel which I wired MCCB was used as the main breaker. I was able to connect trip coils, auxiliary contacts, contacts, inter lock and panel holders with MCCB. In Orange Electric workshop workshop

I had used “ABB”, “Schneider”, “ATION”, and “Orange” brands‟ MCCBs. The Moulded case circuit breakers have been developed for use in commercial and industrial  protection. MCCB has thermal-magnetic operation. Trip current may be adjustable in larger ratings. I was able to identify the main features of a MCCB more than MCB,

27



High short circuit current breaking capacity ( < 20kV).



Used for high current ratings ( < 10000A )



Adjustable current and tripping time rating. Kasun Premarathna

Higher National Diploma in Engineering [HNDE]- Electrical 23-batch



Simultaneous opening and closing of all poles.



Test button which allows periodic testing of the mechanical trips



Accessories such as shunt trip, under-voltage trip, Rotary Operators, motorized kit units, mechanical-electrical interlock, auxiliary contacts are available.

Figure 2.3.4 - MCCB and its auxiliary components

Thermal adjustment (overload)



MCCBs have a wide thermal adjustment range (long delay). The rated current current ( Ir ) it continuously adjustable from 0.4 - 1 of its nominal current (In)

Magnetic Adjustment (short circuit)



Magnetic adjustment (short delay) is available on MCCBs. The magnetic setting (Im) is continuously adjustable from 1 –  10  10 of it‟s In.

Figure 2.3.4 - I - Thermal adjustment 28

Kasun Premarathna

Figure 2.3.4 - II - Magnetic adjustment

Higher National Diploma in Engineering [HNDE]- Electrical 23-batch

2.3.4.1. The Shunt trip coil and Under Voltage Vol tage Tripping Coil (UVT) Shunt and UVT coils are used for remote opening of circuit breaker. The Shunt trip coil consists of an electro-magnetic trip coil that is connected in series with an external field wired switch. When energized the shunt coil,

causing the breaker‟s mechanical latch to move to the open

 position. Shunt coil supply is connected normally open (NO) contact point of the component. Usually EFR, ELR are connected with the shunt coil UVT coil is energized and activated to close the breaker when the coil supply voltage dips below 85% of the rated voltage. When we use

the UVT coil with MCCB‟s we connect coil supply

through the normally close (NC) contact point of the component. At a fault condition, it stops the supply flown through the UVT coil and then the UVT coil trips the breaker. So when a UVT coil is used in a circuit, the MCCB cannot be switched on if there is no current supply.

2.3.4.2. Auxiliary contacts

Auxiliary contacts perform the function of electrically signaling the circuit breaker‟s operating status. The auxiliary contacts change state when the circuit breaker is opened, closed, or tripped.

Figure 2.3.4.2 - Auxiliary contacts and Tripping Coil arrangement 29

Kasun Premarathna

Higher National Diploma in Engineering [HNDE]- Electrical 23-batch



My experience

2.3.4.3. Installation process of MCCB internal accessories I was able to identify the procedure of installation  procedure of the Auxiliary contact, Alarm switch, Shunt trip coil or Under voltage trip coil.

Before the installation process mechanical trip



 button was pushed to trip the MCCB. MCCB must on trip position. 

Then bolt was unscrewed to open the front cover.



Outer cover was removed and identified the correct installing position for auxiliary internal accessory.

The coil was inserted in to that position. Then the



terminal block was installed on the side of MCCB.

The front cover was closed and fixed it with 2



screws. Then coil terminals were connected to the control



circuit.

Figure 2.3.4.3 - Installation of MCCB internal acc essories

30

Kasun Premarathna

Higher National Diploma in Engineering [HNDE]- Electrical 23-batch

2.3.5. The Surge Protection Device The Surge Protection Device (SPD) is a component of the electrical installation protection system. This device is connected in parallel on the power supply circuit of the loads that it has to  protect. It can also be used at all levels of the power supply network. This is the most commonly co mmonly used and most efficient type of overvoltage protection. It is a device used on power systems above 1000V to protect other Equipments from lightning switching & surges. It Does Clamp (limit) the Voltage produced by the Lightning. It only protects equipment electrically in parallel with it.

Figure 2.3.5.1 – SPD device

 – wiring diagram of “OBO” SPD device Figure 2.3.5.2 – wiring

2.3.6. Phase Failure Relay (PFR) Phase failure relay is adjustable under voltage over voltage control device with the option of additional sequence control. If it detects any under voltage, over voltage and phase losses in  power system, the relay coils is energized and trip the MCCB using under-voltage(UVT)trip coil.

Figure 2.3.6 - “ANLY” PFR and its connection diagram 31

Kasun Premarathna

Higher National Diploma in Engineering [HNDE]- Electrical 23-batch

2.3.7. Overload Relay In Orange workshop we used overload relays for the motor control panels as a motor protective device. I observe that, overload relay rela y was used only after the main contactor. contacto r. The overload is a heat operated relay where a coil heats a bimetallic strip and releasing a spring to operate contacts. It has NO & NC auxiliary contact points for the controls. If the overload senses excess current in the load, the coil is de-energized. Electric motors need over current  protection to prevent damage da mage from over-loading the motor, or to protect against short circuits in connecting cables or internal faults in the motor w indings.

Figure 2.3.7 - “LS” Overload relay and symbol

2.3.8. Earth Leakage Relay (ELR) Earth leakage relay monitor the leakage of current to earth on 3 phase electrical systems. The earth leakage relay is used in conjunction with a core balance transformer (CBCT) which is available in five different sizes to cover all sizes of three phase installations.  If make a fault condition, this core balance transformer send a signal to the ELR.   The relays are available with

either a fixed 30mA or 300mA instantaneous trip point or with a user adjustable trip point and time delay both adjustable.

Figure 2.3.8.2 – “DELAB” ELR  32

Kasun Premarathna

Figure 2.3.8.2 –  connection  connection of ELR

Higher National Diploma in Engineering [HNDE]- Electrical 23-batch

2.3.9. Earth Fault Relay (EFR) Earth Fault Relay is used for the protection from earth faults. The function of EFR is as same as ELR. Instead of a CBCT, four separate CT‟s are used to connect an EFR. It is an Electronic Trip Unit, designed to protect the Electrical installation in case of faults or leakage currents beyond a  preset level. The tripping range for both fault current and delay time to be adjusted.

Figure 2.3.9 - “DELAB” EFR  and its connection It has four current transformers. If there is a fault condition, these CTs send a signal to the earth

fault relay. Then its electronic circuit sends a signal to the protection component‟s normally open contact. Then this normally open contact point gets closed. Now that signal is sent to the shunt coil through the normally close contact point. Then the shunt coil is energized and trips the  breaker.



My experience

2.3.9.1. Characteristic settings procedure of Earth Fault Relay I was able to perform the set fault current and trip time of DELAB Earth Fault Relay

33



Press [Select] once to enter mode (it will show the existing value Range 0.03 ~ 30 A)



Set the desired Fault current using the [Up / (+) or Down / (-)] button.



Press [ Select ] to store / confirm new value



Press [ Select ] until mode is displayed.(it will show the ex isting value Range 0.05 ~ 20s)



Set the desired trip time using the [Up / (+) or Down / (-)] button.



Press [ Select ] to store / confirm new value.

Kasun Premarathna

Higher National Diploma in Engineering [HNDE]- Electrical 23-batch

2.4. Measuring Devises Used in the Panels 2.4.1. Current Transformer Transformer Current transformers can reduce or "step-down" current levels from thousands of amperes down to a standard output of a known ratio to either 5 Amps or 1 Amp for normal operation. CTs are used with watt meters, power factor meters, watt-hour meters, protective relays and metering applications, because they are insulated away from any high-voltage power lines. Its primary winding is just a conductor or bus bar placed through a central hole. The secondary winding may have a large number of coil turns wound on a laminated core as shown below.

Figure 2.4.1.2 - Working principle of CT

Figure 2.4.1.1 - Types of CTs

The current transformer should never be open-circuited or operated with no-load attached when the main primary current is flowing. If the ammeter is to be removed, a short circuit should be  placed across the secondary secon dary terminals first. This is because when the secondary is open-circuited open -circuited it will produce a large secondary voltage. Current transformers are available in Ring type, Bushing type, square type, bar type and etc. Accuracy decreases with increased burden (load) or low line current. Accuracy Class of Metering CTs: Metering Class CT Class 0.1 To 0.5

Applications Precision measurements or protection

1

General industrial measurements more sensitive

3

General industrial measurements

5

Approximate measurements Table 2.4.1 - Metering Accuracy Classes of C Ts

34

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Higher National Diploma in Engineering [HNDE]- Electrical 23-batch

 My Experience 

When I was connecting the CT, the ratio of the CT was not matched to the panel current value.



The CT ratio was 150/5A. But the panel MCCB was 63A.



So I used the double turns for reduce the CT ratio as explain below.

Increasing the number of primary turns can decrease the turn‟s ratio. A current transformer with a 300 to 5 turn‟s ratio can be changed to a 150 to 5 turn‟s ratio by passing the primary twice through the window. Also the turn‟s ratio can be either increased or decreased by wrapping wire from the secondary through the window of the current transformer.

Figure 2.4.1.3 - CT connection

2.4.2. Core Balance Current Transformer The Core Balance Current Transformer is a current transformer is used for earth fault protection in grounded three phase systems. It is also known as the zero-sequence current transformer. Each  phase conductor and neutral should pass through the core balance current transformer. It is essential

that

each

conductor

passes

through

the

device

in

the

same

direction.

Figure 2.4.2 - Core Balance Current Cu rrent Transformer

35

Kasun Premarathna

Higher National Diploma in Engineering [HNDE]- Electrical 23-batch



Working principle of Core Balance CT

The net resultant flux being zero does not induce any current in the secondary of the transformer. Thus the secondary current of the core balance current transformer when all the three phases are healthy is zero. When an earth fault occurs in one of the phases, the zero-sequence fault current which flows is not cancelled by the flux of the other two phases and hence induces a current in the secondary. The core balance current transformer can be connected to an earth fault relay which can be used to generate the tripping signal.

2.4.3. Indicator Indicators are used to get information about states of equipment such as ON (Green), OFF (red), TRIP (Orange). Indicators are available in read yellow blue and orange and 12V to 230V.

2.4.4. Ammeter An ammeter is a measuring a measuring instrument used to measure the electric the electric current in a circuit. Current  circuit. Current transformers and ammeters are used together as a matched pair in which the design of the current transformer is such as to provide a maximum secondary current corresponding to a full-scale deflection on the ammeter. For most current transformers the primary and secondary currents are expressed as a ratio such as rated current : 5A.

2.4.4.1. Connecting process of an Ammeter 

I was able practice connecting process of the Ammeter in to the panels.



In 3 phase system, 3 position selector switch was used to select the 3 phases R, Y or B.



CTs were connected in to the selector switch.



The selector switch was connected with the Ammeter A1 and A2.

Figure 2.4.3 –  Connecting  Connecting diagram of an Ammeter

36

Kasun Premarathna

Higher National Diploma in Engineering [HNDE]- Electrical 23-batch

2.4.5. Voltmeter A voltmeter is an instrument used for measuring electrical potential difference between two  points in an electric circuit. Analog voltmeters move a pointer across a scale in proportion to the voltage of the circuit. The voltmeter selector switch is used to select the two phases or phaseneutral in 3 phase system.

Figure 2.4.4 –  voltmeter  voltmeter and selector

2.4.6. KWH Meter (Energy meter) KWH Meter is used to measure the kW power. Mainly we use two types of KWh meters. Those are single-phase kWh meters and three phase kWh meters. These three phase & single-phase meters are can be dividing again like this C/T type and direct type. Mostly we use C/T type energy meters. In some panels, used digital di gital KWH meters.

2.4.7. Digital Power Analyzer Power analyzers accurately measure electrical power characteristics of the system. Power analyzers, also called power meters or watt meters, provide precise measurements of power supply system. This is useful for getting to power consumption and many more values of the system.

I was able to refer metering performed of Schneider PM 700 digital analyzer,

37



Current - (per phase/ neutral) min/max Current demand: present



Voltage - (line-line/ line-neutral) per phase, min/max



Power: - real (kW), reactive (kvar), apparent (kVA), per-phase, total



Energy: - real (kWh), reactive (kvarh), apparent (kVAh)



Signed power factor:- total, min/max



Frequency: - present, min/max

Kasun Premarathna

Higher National Diploma in Engineering [HNDE]- Electrical 23-batch

2.5. Switching Devises Used in the Panels

2.5.1 Relay A relay is a switching device. Relays are used where it is necessary to control a circuit by a low power signal with complete electrical isolation between control and controlled con trolled circuits or where several circuits must be controlled by one signal.

Figure 2.5.1 –  relay  relay and relay base

Relay consists with coil, normally open and normally closed contact points. When current starts flowing through the control coil, the electromagnet starts energizing and contact points are changed their position. Coil voltage can be 12V to 230V AC or DC. Also contact current rating is important factor. According to the contact pin arrangement, relays are categorized as 8 pins, 11 pins, 14 pins and etc. relay is fixed with its base.

2.5.2. Contactor I was able to identify the contactor construction and usages, because contactor was used in every motor control panel. It was used for the high power application switching on power circuit. Also I connected timers, auxiliary contact points (side and top), timers and mechanical interlock to the

contactors according to the requirement. In Orange Electric workshop I had used “ABB”, “Schneider” and “LS” brands‟ contactors. Contactor is also a type of relay. The contactor consists with normally Open contacts and also auxiliary contact points. Also it can connect auxiliary contact points (side and top), timers and mechanical interlock.

38

Kasun Premarathna

Higher National Diploma in Engineering [HNDE]- Electrical 23-batch

Figure 2.5.2.1 - “ABB” contactor 

Figure 2.5.2.2 –  Auxiliary  Auxiliary

A contactor consists of mainly 2 parts-Fixed and movable jaws. the fixed jaws are firmly connected with the circuit and is a provided with a coil having movable jaw as soon as current current is allowed to flow from the circuit the coil gets charged and due to electromagnetic effect it attracts the movable metal jaw, thus the circuit is complete with the contact provided by the movable  jaw. This is the functioning of contactor. When current through the coil loss, coils demagnetize and open the contacts. The coil consist with shaded pole core, because of avoiding the current zero position of the AC supply. The current rating of the contactor is depending on its category. The categories in standard are described as: 

AC-1 - Non-inductive or slightly inductive loads, resistance furnaces



AC-2 - Starting of  slip-ring  slip-ring motors: starting, motors: starting, switching-off



AC-3 - Starting of  squirrel  squirrel cage motors. (Inductive motors. (Inductive and resistive loads)



AC-4 - Starting of squirrel-cage motors with inching and plugging duty.

2.5.3. Timer Relay Timer relays are simply control relays with a time delay built in. Their purpose is to control an event based on time. The difference between relays and time delay relays is when the output contacts open & close: on a control relay, it happens when voltage is applied and removed from the coil; on time delay relays, the contacts can open or close before b efore or after some time delay.

Figure 2.5.3.1- Timers

39

Kasun Premarathna

Figure 2.5.3.2 - Analog timer internal connection

Higher National Diploma in Engineering [HNDE]- Electrical 23-batch

The timers are divided into many categories acc ording to their performance,

ON delay



Upon application of input voltage, the time delay begins. At the end of the time delay, the output is energized. Input voltage must be removed to reset the time delay relay & de energized the output. 

OFF delay

Upon application of input voltage, the time delay relay is ready to accept a trigger. When the trigger is applied, the output is energized. Upon removal of the trigger, the time delay begins. At the end of the time delay, the output is de-energized..

According to the requirement, Timer relay characteristics are selected according to fallowing  parameters. 

Input coil current range - 12v to 440V (DC / AC)



Time settings - seconds, minutes, hours, days, month, years



Analog, digital, 24 hours, programmable, star-delta, etc.



Pin configuration - 8 pin, 11 pins, and 14 pins etc.

2.5.4. Push Buttons The push-buttons & selector Switches are momentary contact device used for giving the ON and OFF commands. Push button has normally open (NO) contacts and normally closes (NC) contacts. Some selector switch has 2-stay part and some has 3-stay part and also spring return selector switches switches are available.

Emergency Push Button is another type type of push button. Those

 push buttons can connect auxiliary contact points.

Figure 2.5.4 –  Push  Push button and emergency button

2.5.5. Selector Switches Selector switch has 2 parts or 3 parts. It is used to select the power path.

40

Kasun Premarathna

Higher National Diploma in Engineering [HNDE]- Electrical 23-batch

2.6. Cables

In panel wiring we used “Orange Cable” and “Kalani Cable” for requirements. I was able to refer the cable current caring capacity table and selected the wires for panel wiring. In panel wiring normally we used PVC insulated type single core copper wires. The selection of cables for panel wiring was best done with reference to the latest and specific

manufacturer‟s cable data and application guides with tables giving cable dimensional, and current rating information. The cross-sectional area of the conductors chosen should be of the optimum size to carry the specified load current or short circuit short term current without overheating and should be within the required limits for voltage drop.

Figure 2.6 –  PVC  PVC insulated cable

2.6.1. Cable Insulation Materials PVC (Polyvinyl Chloride)  –  is  is the most commonly used thermoplastic insulator for cables. It



is cheap, durable and widely available. PVC Normal operating temperatures are typically 0C

0C

 between 75  and 100  (depending on PVC type) PE (Polyethylene)  –  is   is part of a class of polymers called polyolefin. Polyethylene has lower



dielectric losses than PVC and is sensitive to moisture under voltage stress (i.e. for high voltages only).

2.6.2. Cable Lug Lugs were use to connect the wire to terminals. Cable lug was connected with connecting end of the cable using wire crimping tool. Suitable Cable lug sizes depend on the wire cross section area. In our workshop were so many types of lug. Such as Normal lug, U lug, and O lug.

Figure 2.6.2 –  cable  cable Lugs

41

Kasun Premarathna

Higher National Diploma in Engineering [HNDE]- Electrical 23-batch

2.6.3. Cable Numbering Tube  Numbering tubes are used to identify the cable in control circuit. Tube Printer is used to  print the numbers.

Figure 2.6.3 - Cable Numbering Tube

2.6.4. Current ratings of single core PVC insulated cable

Cross sectional 2 area (mm )

 Nominal conductor size (mm)

1 phase Current carrying capacity (A)

3 phase Current carrying capacity (A)

1.0

1/1.13

13.8

12

1.5

1/1.38

18

16

1.5

7/0.50

18

14

2.5

7/0.67

24

21

4

7/0.85

32

28

6

7/1.04

41

37

10

7/1.35

57

51

16

7/1.70

76

70

25

19/1.35

104

90

35

19/1.53

128

113

50

19/1.78

151

138

70

19/2.14

192

175

95

37/1.78

232

210

120

37/2.03

269 269

245

150

37/2.35

300 300

260

185

37/2.52

351 351

305

240

61/2.25

412 412

360

300

61/2.52

472 472

410

400

61/2.85

562 562

468

500

61/3.20

595 595

520

Table 2.6.4 - Current ratings of single core P VC insulated cable

42

Kasun Premarathna

Higher National Diploma in Engineering [HNDE]- Electrical 23-batch

2.7. Bus bars The bus bar is a strip or bar of copper  brass or aluminum that conducts electricity within a switchboard, distribution switchboard, distribution board, substation, board, substation, battery  battery bank, or bank, or other electrical apparatus. Its main  purpose is to conduct a substantial current of electricity. The cross-sectional size of the bus bar determines the maximum amount of  current  current that can be safely carried

Figure 2.7 –  Bus  Bus bars

2.7.1. Bus bar sizes and current capacity Size (inch)

Current capacity (A)

width x height

3/4 x 1/4

239

Copper tape 1x1/8

161

1 x 1/4

320

1 ¼ x1/4

399

1 1/4 x 3/8

602

1 ½ x 1/4

479

1 ½ x 3/8

722

2 x 1/4

640

2 x 3/8

965

2 1/4 x 1/4

718

2 ½ x 1/4

798

3 x 1/4

960

4 x 1/4

1280

Table 2.7.1 - Bus bar current capacity

43

Kasun Premarathna

Higher National Diploma in Engineering [HNDE]- Electrical 23-batch

2.8. Distribution Panels 2.8.1 Main Distribution Panel Main Distribution panel Board (MDB) is a panel or enclosure is used to distribute electrical  power to numerous individual circuits or consumer points, is taken in from the transformer or an upstream panel. An MDB typically has a single or multiple incoming power sources and includes main circuit breakers and residual current or earth leakage protection devices. A MDB is comprised of a free standing enclosure, a bus bar system, MCCB's, metering and support equipments and required current transformers. Panels are assembled in a systematic manner such as incomer section and outgoing section.

Figure 2.8.1 - Main Distribution panel

2.8.2. Sub Distribution Panel The Main Distribution panel Board then feeds to the Sub distribution boards, which is installed generally at the point where a large distribution cable terminates and several smaller sub-circuits start. The voltages and current ratings ratings are low. These are the switchboards that although similar construction, are larger than a final distribution board circuit. The boards are installed midway through the power distribution system, at the point in a large distribution cable ends, and several smaller starting sub-circuits.

44

Kasun Premarathna

Higher National Diploma in Engineering [HNDE]- Electrical 23-batch

Figure 2.8.2 - Sub Distribution panel



My Experience

2.8.3. The pump house distribution panel wiring procedure I was able to create an electrical design & wire the fallowing distribution panel in the orange workshop

Figure 2.8.3 -The pump house distribution panel wiring diagram

45

Kasun Premarathna

Higher National Diploma in Engineering [HNDE]- Electrical 23-batch



This distribution panel was designed for pump house. In this pump house all the pumps will not operate at the same time, some pumps are using as the standby pumps.



“ABB” 4 poles 125A MCCB was used as the main breaker.



“DELB” ELR with shunt release coil was used as the protection device and “HOBUT” 200/5A core balance CT is used to get current inputs.



According to the customer requirement, emergency stop switch was connected with shunt coil.



2

The 35mm  copper PVC insulated wires (Kalani cables) were used to wire from main MCCB 2

2

2

to bus bar chamber. Thence 16mm  for 63A, 10mm  for 40A and 4mm  for 16A wires were used. 

R, Y, B incoming indicators were attached to the panel door through the 2A fuse.

Problems faced during this panel wiring This panel box was designed 250x400x150 size. The 150mm was not enough for the



“HOBUT” 200/5A core balance CT. so that I had to cut the cover plate of the panel, before the wired.

46

Kasun Premarathna

Higher National Diploma in Engineering [HNDE]- Electrical 23-batch

2.9. Changeover Panels In Orange workshop I observed Manual type and Auto type changeover panels. In Automatic Changeover Panels we used several types of Auto transfer Switches (ATS). MCCB type, Contactor type and Changeover type were some of them. A changeover panel is operating on a mains power failure system. There are two types of changeover panels.

2.9.1. Manual Changeover Panel In manual changeover panels rotary manual switch with centre off position is used to enable selection of 2 different different supplies. Most commonly a mains mains supply and a back-up generator supply.

2.9.2. Automatic Changeover Panel (ATS panel) The automatic panel, when the main supply is interrupted on one or all phases (after an adjustable delay period) the generator sets will start-up automatically. After an initial warm-up  period (adjustable) the generators will synchronize with each other by means of motorized circuit  breakers or contactors onto a common bus bar. When the power will come, the motorized change-over switch will be closed and the load will be connected to the main the main supply.

Figure 2.9.2 - Automatic Changeover Panel

47

Kasun Premarathna

Higher National Diploma in Engineering [HNDE]- Electrical 23-batch



My Experience

2.9.3. Automatic Changeover Panel wiring I was able to wire the below control circuit of Automatic Changeover panel. The panel consisted

with “Telegarn” ATS changeover with motorized kit. This circuit was designed to get continues power supply from CEB or generator. According to this panel circuit it can automatically switch on the generator when CEB power failure.

Figure 2.9.3 - Automatic Changeover Panel control wiring diagram

Important points

The “Telegarn” ATS changeover unit was used separate auxiliary supply from CEB side



(used pin no 01 and 02) and generator (used pin no 03 and 04). There was two selector switches, one was used to Auto-Manual selector other one was used



to select CEB or Generator in manual mode. Phase Failure Relay (PFR) was used to detect the supply conditions in CEB and generator.



48

Kasun Premarathna

Higher National Diploma in Engineering [HNDE]- Electrical 23-batch

th

R2 relay was used to give a CEB ON signal to the 11   pin of changeover motorized kit



3

through open point (NO) of R2 6  . th

R3 relay was used to give a Generator ON signal to the 10  pin of changeover motorized kit



3

through open point (NO) of R36  . T4 timer was used to avoid the sudden change from generator supply to the CEB supply, if



CEB supply is changing quickly due to voltage fluctuation, T4 will keep generator supply continuously. th



12  pin of the motorized kit was used to give OFF signal in to the changeover.



For interlock purpose R3 1  and R2 1 closed points were used in the circuit.



T4

5

1

4

5

3

  and R17  closed points were used in generator starting control supply for avoid the

generator start manual or auto when the CEB supply is connected in manual or auto mode.

49

Kasun Premarathna

Higher National Diploma in Engineering [HNDE]- Electrical 23-batch

2.10. Motor Control Panels Motor Control panel consist of different motor starting methods such as Direct Online Starter (DOL), Star-Delta Starter, Auto Transformers, Variable Speed Drives or Variable Frequency Drives. Mainly used DOL and Star-Delta methods,

2.10.1. Direct Online Starter (DOL) panel This is the most common method of starting low power induction motors, where the starter is connected directly across the three phase of the supply. However, the starting current at the moment of switching direct-on-line can be as high as 6-8 times the rated current. A Direct Online Motor Starter (DOL) consists of following components.

o

A Circuit Breaker or Fuse(F)

o

A Contactor (K1)

o

An Overload Relay (OL1)

o

start button (S1)

o

Stop button (S0)

Figure 2.10.1 - Power circuit and control circuit of DOL panel

Typically, the contactor of the DOL circuit is controlled by separate start and stop push buttons. When the start push button is pressed, the current flow through the control circuit and the contactor coil which will energize the contactor coil and then the NO contactor contact get closed and self holding. So the current is passed to the motor. When the stop button is pressed or the over load coil is operated, the control circuit get broken and the contactor drops out.

50

Kasun Premarathna

Higher National Diploma in Engineering [HNDE]- Electrical 23-batch



My Experience

2.10.2 Cooling tower panel wiring I was able to wire the cooling tower panel according to the given details. This panel is consisting with two 5.5kW pumps and a 1.5kW cooling fan motor. The two main motors are manually selectable. All three motors are wired in DOL method.

Figure 2.10.2.1 - Power circuit of cooling tower panel

Figure 2.10.2.2 - Control circuit of cooling tower panel

51

Kasun Premarathna

Higher National Diploma in Engineering [HNDE]- Electrical 23-batch

Calculations Main pump and standby pump o

Full load current

P

=

=

V √3 CosΦ o

 pump over load

o

 pump contactor = 12A

o

MCB

rating

3

5.5 * 10

=

8.6 A

=

2.3 A

415 * √3 * 0.8

= 8A to 12A

= 16A

Cooling fan motor o

Full load current

P

=

=

V √3 CosΦ o

over load

= 2A to 4A

o

contactor

= 4A

o

MCB

= 6A

rating

3

1.5 * 10

415 * √3 * 0.8

Important points



Main MCB was selected as 25A “Orange” MCB.



Main RCCB was selected as 32A-100mA “Orange” RCCB.



Two position selector switch was used to selector



Run and trip indicators were used, trip indicators were connected through normally open  point (NO 97-98). The main motor and standby motor only work after the cooling fan is on. For that purpose,



the control circuit supply for the main and standby pumps were connected through the normally open point (NO) of the cooling fan motor contactor (KM3). 

1 x 1/8 cupper tape bus bar chamber was designed for distribute the MCBs.



All the power circuit wirings were going on 4mm CU/PVC wires.

2

52

Kasun Premarathna

Higher National Diploma in Engineering [HNDE]- Electrical 23-batch

2.10.3. Star-Delta Starter Panel

When very large (< 5HP) motors are started by DOL, they cause a disturbance of voltage on the supply lines due to large starting current surges. To limit the starting current surge, large induction motors are started at reduced voltage and then have full supply voltage reconnected when they run up to near rotated speed. Star-Delta starter is the reduced voltage starting method. This type reduces phase voltage to about 58% of the running voltage, which reduce the current

and the motor‟s torque.

Figure 2.10.3 –  Power  Power circuit and Control circuit of star delta panel

The Star/Delta starter is manufactured from three contactors, an on delay timer and a thermal

overload. The currents through the winding are 1/√ 3 of the current in the line. There are two contactors that are close during run, often referred to as the main contractor and the delta contactor. These are AC3 rated at 58% of the current rating of the motor. The third contactor is the star contactor and that only carries star current while the motor is connected in star. The current in star is one third of the current in delta, so this contactor can be AC3 rated at 1/3 (33%) of the motor rating. In the star-delta starting method, firstly the motor starts as star after 80% of its full speed it can run as delta. The one delay timer is sated that time of 80% of its full speed.

53

Kasun Premarathna

Higher National Diploma in Engineering [HNDE]- Electrical 23-batch

Full load current =

P

V √3 Cos Φ





Main over Load Relay (OL)= full load current x 1/√3



Size of Main and Delta Contractor (K1 & K2)= full load current x 1/√3



Star Contactor (K3) = full load current x 1/3

My Experience

2.10.4. Fire pump panel wiring 

I was able to create electrical design & wire wi re the fire pump panel.



Two main pumps of 37kW and a jockey pump of 2.2kW were used for the panel.



The 37kW pumps are connected as star-delta and 2.2kW pump as direct online connection.

Calculation For Main pumps o

Full load current

P

=

3

37 * 10

=

V √3 Cos Φ

=

64.3 A

415 * √3 * 0.8

o

Main & delta contactors = Full load current

* 1/√3 = 64.3 * 1/√3 = 37.3 A

o

Star contactor

= Full load current * 1/3

o

Main pump over load

= 30A to 42A

o

Main pump MCCB

=100A

= 64.3* 1/3

= 21.4 A

For jokey pump o

Full load current

P

=

V √3 Cos Φ

54

o

Jokey pump contactor

o

Jokey pump over load = 3A to 8A

o

Jokey pump MCCB

Kasun Premarathna

=

3

2.2 * 10

=

3.8 A

415 * √3 * 0.8

= 4A

= 6A

Higher National Diploma in Engineering [HNDE]- Electrical 23-batch

Figure 2.10.4 – Control Control circuit of Fire pump panel

Important points The panel was designed with two pressure sensors, when sensor 1 will gives signal to the



 panel, main pump1 will operates. If pump1 will overload, the pump 2 will operates. The Pump 1 or pump 2 needs more power, sensor 2 will gives signal to jokey pump operation. 

“ABB” MCCBs, over loads and contactors were used.



“Omron” 11 pin relays and “ANLY” 8 pin timers are used.



The panel was designed as auto and manual operation.



Two position selector switches were used for auto manual selector and pump selector.

55

Kasun Premarathna

Higher National Diploma in Engineering [HNDE]- Electrical 23-batch

Problems faced during this panel wiring

The “ABB” contactor has only one external normally open (NO) contact point and no any



normally close (NC) contact point. I had to fallowed one of below way to s olve this, o

Can connect auxiliary contact points to the contactor.(side contact or top contact)

o

Can use mechanical interlock instead to the contact point interlock.

o

Can connect another relay with parallel to the contactor.

I was able to connect auxiliary au xiliary contact points. Other solutions are not suitable for this p anel.

When the panel was being tested, the one timer didn‟t operate correctly.



o

According to the 8 pin timer connection, point 1 and point 8 are act as common. If  point 1 is connected to the incoming side, the point 8 must be connected to the incoming side. Otherwise timer will not operate correctly.

Figure 2.10.4.1 –  Timer  Timer connection of fire pump panel

56

Kasun Premarathna

Higher National Diploma in Engineering [HNDE]- Electrical 23-batch

2.11. Power Factor Correction Capacitor Bank

Various industries and power system loads are inductive that take lagging current which decrease the system power factor. The poor power poor  power factor increases the current the current flowing in conductor and thus copper loss increases. Further high reactive power flows through the line, the apparent  power (KVA) and cost of electricity bill is high. The power factor of a circuit may also be defined as the ratio of active power (KW) to the apparent power (KVA). The lagging reactive power is responsible for the low power factor. It is clear from the power triangle that smaller the reactive power component, the higher is the power factor.

Figure 2.11 –  Power  Power factor triangle Figure 2.11.1 –  Capacitor  Capacitor Bank The power factor can be improved by connecting capacitors in shunt with the system operating at lagging power factor. These static capacitors provide leading current. A number of capacitor units are combined to capacitor bank arrangement. Capacitor bank connected in shunt with load. They improve the electrical supply quality and increase the efficiency of the system. Also reduce reactive power and cost effective. Power factor correction is an investment that helps to improve

company‟s profit performance.  The capacitor bank with automatic regulation offers the most economical solution. Capacitor bank offers several advantages over other methods of power factor improvement.

57



Losses are low in static capacitors.



There is no moving part, therefore need low maintenance.



They are lightweight so it is can be easy to install.

Kasun Premarathna

Higher National Diploma in Engineering [HNDE]- Electrical 23-batch

2.11.1. Components used in Capacitor Bank  

Power factor correction capacitors Capacitors are made in metalized polypropylene film (PFC). For three-phase loads, three-phase capacitors are used. Normally three phase capacitor is interconnected three capacitors in delta. Capacitors are rated in kVAR. Common factors of the capacitor are Rated Voltage, kVAR Range, frequency, temperature, and harmonics.

Figure 2.11.1.1 –  Power  Power capacitor



Capacitor Switching Contactor When we were selecting contactor, consider about Rated current (Ie), Reactive power (kVAR), voltage category and Thermal current (Ith). Capacitor switching contactors consist with contacts and damping resistors. The capacitor switching contactor designed switch the capacitor first through contact block of three contacts in series with quick discharge damping resistor to limit to inrush current. Normally rated current is carried by main contacts, which after closing after

Figure 2.11.1.2 –  Capacitor  Capacitor switching contactors



about 5 ms, effectively bypass the damping resistor.

Automatic power factor controller Digital power factor controller is used to control to capacitor bank. Measurement of the required reactive power and control the capacitor switching according to the power factor desired or preset value. Also indication of power factor, display the number of capacitors steps switched into the system and preset parameters of the system. Disconnect the capacitors capacitors when a system voltage drop

Figure 2.11.1.2- Automatic  power factor factor controller

58

Kasun Premarathna

occurs. Power factor controller is selecting according to number of switching steps.

Higher National Diploma in Engineering [HNDE]- Electrical 23-batch

Discharge resistor



Capacitors should be discharged to