��������� �� ����� ������ ��������

RAVINDRA P. SINGHPrincipal

Applied College of Management and EngineeringPalwal, Faridabad

��������� ������������ ��������

New Delhi-1100012009

SWITCHGEAR AND POWER SYSTEM PROTECTIONRavindra P. Singh

© 2009 by PHI Learning Private Limited, New Delhi. All rights reserved. No part of this book may bereproduced in any form, by mimeograph or any other means, without permission in writing from thepublisher.

ISBN-978-81-203-3660-5

The export rights of this book are vested solely with the publisher.

Published by Asoke K. Ghosh, PHI Learning Private Limited, M-97, Connaught Circus,New Delhi-110001 and Printed by Raj Press, New Delhi-110012.

�������������������� ����������� ������ �����������������������������������

��������������������������

Preface xv

Part A: Switchgear

1. DEFINITIONS AND TERMINOLOGY 3�61.1 Introduction 3

2. BASICS OF SWITCHGEAR 7�392.1 Introduction 72.2 Fuses 7

2.2.1 Types of Fuses 82.3 Isolators 10

2.3.1 Types of Isolators 102.4 Earthing Switches 142.5 Contactors 15

2.5.1 Types of Contactors 152.6 Circuit-Breakers 17

2.6.1 Insulating Fluids 172.6.2 Properties of Insulating and Arc Quenching Materials 172.6.3 Initiation of Arc in Circuit-breakers 182.6.4 Arc Interruption 182.6.5 Current Interruption 192.6.6 Effect of Power Factor 192.6.7 Parallel Capacitances 202.6.8 Arc Interruption Theories 212.6.9 Current Chopping 222.6.10 Resistance Switching 242.6.11 Capacitance Current Breaking 242.6.12 Restriking Voltage 25

vii

��������

���� ��������

2.6.13 Current Zero Pause 342.6.14 Main Parts of Circuit-breakers 352.6.15 Main Types of Circuit-breakers 352.6.16 Rating of Alternating Current Circuit-breaker 352.6.17 Miniature Circuit-breaker (MCB) 352.6.18 Residual Current Circuit-breaker (RCCB) 37

Exercises 38

3. HIGH VOLTAGE CIRCUIT-BREAKERS 40�593.1 Introduction 403.2 Bulk Oil Circuit-breaker (BOCB) 41

3.2.1 Advantages of Bulk Oil Circuit-breaker 413.2.2 Limitations of Bulk Oil Circuit-breaker 413.2.3 Construction of Bulk Oil Circuit-breaker 42

3.3 Minimum Oil Circuit-breaker (MOCB) 433.3.1 Advantages of Minimum Oil Circuit-breaker 453.3.2 Limitations of Minimum Oil Circuit-breaker 45

3.4 Air Circuit-breaker (ACB) 453.5 Air Blast Circuit-breaker (ABCB) 46

3.5.1 Construction of Air Blast Circuit-breaker 463.5.2 Advantages of Air Blast Circuit-breaker 473.5.3 Limitations of Air Blast Circuit-breaker 48

3.6 Vacuum Circuit-breaker (VCB) 483.6.1 Construction of Vacuum Circuit-breaker 483.6.2 Advantages of Vacuum Circuit-breaker 493.6.3 Limitations of Vacuum Circuit-breaker 50

3.7 Sulphur Hexafluoride Gas (SF6) Circuit-breaker 503.7.1 Construction of SF6 Circuit-breaker 513.7.2 Operation of SF6 Circuit-breaker 523.7.3 Advantages of SF6 Circuit-breaker 523.7.4 Limitations of SF6 Circuit-breaker 53

3.8 High Voltage Direct Current (HVDC) Circuit-breaker 533.9 Autoreclosing 543.10 Circuit-breaker Testing 54

3.10.1 Test Equipment 543.10.2 Test Method 55

Exercises 58

4. CURRENT-LIMITING REACTORS 60�704.1 Introduction 604.2 Types of Reactors 61

4.2.1 Dry Air-cored Reactor 614.2.2 Oil-immersed, Non-magnetically-shielded Reactor 624.2.3 Oil-immersed, Magnetically-shielded Reactor 624.2.4 Saturated Reactor 62

4.3 Reactance Calculation 634.4 Applications of Reactors 644.5 Short Circuit, Current-limiting Coupling Circuit (SCCLCC) 64

Exercises 69

�������� ��

Part B: Power System Protection

5. INTRODUCTION 73�1015.1 Structure of a Power System 735.2 What Is the Need for Power System Protection? 745.3 Development of Protective Relays 75

5.3.1 Recent Developments 765.3.2 How do Protective Relays Operate? 77

5.4 Basic Philosophy of Protection Schemes 785.4.1 Protection Zones 785.4.2 Primary Protection 795.4.3 Back-up Protection 795.4.4 Quality Requirements of Protection 80

5.5 Classification of Relays Based on Their Construction 825.6 Electromechanical Relays 82

5.6.1 Attracted Armature Type 825.6.2 Induction Disc Relay 845.6.3 Induction Cup Relay 865.6.4 Printed Disc Relay 875.6.5 Moving Coil Relay 885.6.6 Polarised Moving Iron Relay 885.6.7 Demerits of Electromechanical Relays 89

5.7 Thermal Relays 895.8 Transductor Relays 905.9 Rectifier Bridge Relays 905.10 Electronic Relays 905.11 Classification of Relays Based on Their Functions 915.12 Current Transformers (CTs) 915.13 Potential Transformers (PTs) 935.14 Summation Transformers 935.15 Phase–sequence Current Segregating Network 935.16 Routine Checks for Sensitivities and Secure Performance 945.17 Basic Definitions 95

Exercises 100

6. PROTECTION SCHEMES 102�1296.1 Overcurrent Relaying 102

6.1.1 Instantaneous Overcurrent Relays 1026.1.2 Time-delayed Overcurrent Relays 1036.1.3 Definite Time Overcurrent Relays 1036.1.4 Inverse Time Overcurrent Relays 1046.1.5 Inverse Definite Minimum Time Overcurrent Relays [IDMT-Type O/C Relay] 1056.1.6 Relay Coordination 105

6.2 Differential Relaying 1166.2.1 Circulating Current Differential Relays 1166.2.2 Opposed Voltage Differential Relays 1166.2.3 Biased (Percentage) Differential Relays 117

Switchgear And Protection

Publisher : PHI Learning ISBN : 9788120336605 Author : Ravindra P Singh

Type the URL : http://www.kopykitab.com/product/6185

Get this eBook