Electrical Power Equipment Maintenance and Testing - 2nd Edition PDF

Preview

Summary

POWER ENGINEERING Series Editor H. Lee Willis Quanta Technology Raleigh, North Carolina Advisory Editor Muhammad H. Rashid University of West Florida Pensacola, Florida 1. Power Distribution Planning Reference Book, H. Lee Willis 2. Transmission Network Protection: Theory and Practice, Y. G. Paitha...

Description

POWER ENGINEERING Series Editor

H. Lee Willis Quanta Technology Raleigh, North Carolina Advisory Editor

Muhammad H. Rashid University of West Florida Pensacola, Florida

1. Power Distribution Planning Reference Book, H. Lee Willis 2. Transmission Network Protection: Theory and Practice, Y. G. Paithankar 3. Electrical Insulation in Power Systems, N. H. Malik, A. A. Al-Arainy, and M. I. Qureshi 4. Electrical Power Equipment Maintenance and Testing, Paul Gill 5. Protective Relaying: Principles and Applications, Second Edition, J. Lewis Blackburn 6. Understanding Electric Utilities and De-Regulation, Lorrin Philipson and H. Lee Willis 7. Electrical Power Cable Engineering, William A. Thue 8. Electric Systems, Dynamics, and Stability with Artificial Intelligence Applications, James A. Momoh and Mohamed E. El-Hawary 9. Insulation Coordination for Power Systems, Andrew R. Hileman 10. Distributed Power Generation: Planning and Evaluation, H. Lee Willis and Walter G. Scott 11. Electric Power System Applications of Optimization, James A. Momoh 12. Aging Power Delivery Infrastructures, H. Lee Willis, Gregory V. Welch, and Randall R. Schrieber 13. Restructured Electrical Power Systems: Operation, Trading, and Volatility, Mohammad Shahidehpour and Muwaffaq Alomoush 14. Electric Power Distribution Reliability, Richard E. Brown 15. Computer-Aided Power System Analysis, Ramasamy Natarajan

DK4058_C000.indd i

11/20/2008 10:17:56 AM

16. Power System Analysis: Short-Circuit Load Flow and Harmonics, J. C. Das 17. Power Transformers: Principles and Applications, John J. Winders, Jr. 18. Spatial Electric Load Forecasting: Second Edition, Revised and Expanded, H. Lee Willis 19. Dielectrics in Electric Fields, Gorur G. Raju 20. Protection Devices and Systems for High-Voltage Applications, Vladimir Gurevich 21. Electrical Power Cable Engineering, Second Edition, William Thue 22. Vehicular Electric Power Systems: Land, Sea, Air, and Space Vehicles, Ali Emadi, Mehrdad Ehsani, and John Miller 23. Power Distribution Planning Reference Book, Second Edition, H. Lee Willis 24. Power System State Estimation: Theory and Implementation, Ali Abur 25. Transformer Engineering: Design and Practice, S.V. Kulkarni and S. A. Khaparde 26. Power System Capacitors, Ramasamy Natarajan 27. Understanding Electric Utilities and De-regulation: Second Edition, Lorrin Philipson and H. Lee Willis 28. Control and Automation of Electric Power Distribution Systems, James Northcote-Green and Robert G. Wilson 29. Protective Relaying for Power Generation Systems, Donald Reimert 30. Protective Relaying: Principles and Applications, Third Edition, J. Lewis Blackburn and Thomas J. Domin 31. Electric Power Distribution Reliability, Second Edition, Richard E. Brown 32. Electrical Power Equipment Maintenance and Testing, Second Edition, Paul Gill

DK4058_C000.indd ii

11/20/2008 10:17:57 AM

ELECTRICAL POWER EQUIPMENT MAINTENANCE AND TESTING SECOND EDITION

Paul Gill

Boca Raton London New York

CRC Press is an imprint of the Taylor & Francis Group, an informa business

DK4058_C000.indd iii

11/20/2008 10:17:57 AM

CRC Press Taylor & Francis Group 6000 Broken Sound Parkway NW, Suite 300 Boca Raton, FL 33487-2742 © 2009 by Taylor & Francis Group, LLC CRC Press is an imprint of Taylor & Francis Group, an Informa business No claim to original U.S. Government works Printed in the United States of America on acid-free paper 10 9 8 7 6 5 4 3 2 1 International Standard Book Number-13: 978-1-57444-656-2 (Hardcover) This book contains information obtained from authentic and highly regarded sources. Reasonable efforts have been made to publish reliable data and information, but the author and publisher cannot assume responsibility for the validity of all materials or the consequences of their use. The authors and publishers have attempted to trace the copyright holders of all material reproduced in this publication and apologize to copyright holders if permission to publish in this form has not been obtained. If any copyright material has not been acknowledged please write and let us know so we may rectify in any future reprint. Except as permitted under U.S. Copyright Law, no part of this book may be reprinted, reproduced, transmitted, or utilized in any form by any electronic, mechanical, or other means, now known or hereafter invented, including photocopying, microfilming, and recording, or in any information storage or retrieval system, without written permission from the publishers. For permission to photocopy or use material electronically from this work, please access www.copyright.com (http:// www.copyright.com/) or contact the Copyright Clearance Center, Inc. (CCC), 222 Rosewood Drive, Danvers, MA 01923, 978-750-8400. CCC is a not-for-profit organization that provides licenses and registration for a variety of users. For organizations that have been granted a photocopy license by the CCC, a separate system of payment has been arranged. Trademark Notice: Product or corporate names may be trademarks or registered trademarks, and are used only for identification and explanation without intent to infringe. Library of Congress Cataloging-in-Publication Data Gill, Paul, 1942Electrical power equipment maintenance and testing / Paul Gill. -- 2nd ed. p. cm. ISBN 978-1-57444-656-2 (alk. paper) 1. Electric power systems--Testing. 2. Electric power systems--Maintenance and repair. I. Title. TK401.G55 2008 621.31’0420287--dc22

2008029371

Visit the Taylor & Francis Web site at http://www.taylorandfrancis.com and the CRC Press Web site at http://www.crcpress.com

DK4058_C000.indd iv

11/20/2008 10:17:57 AM

Liability This textbook and instructions offered in it are designed to acquaint students and readers with accepted good practice for maintenance, operation, and testing of electrical equipment and/or systems. This book does not purport to be complete nor is it intended to be specific for the products of any manufacturer, testing procedures, or maintenance routines. The publisher, the author, companies, and other organizations referenced in this book will not accept any responsibility and liability whatsoever for work undertaken on the basis of this text. The sole purpose of this book is to impart knowledge on the subjects covered in the book. All work undertaken based on this text is the sole responsibility of the reader and user of the book. The manufacturer’s operating, maintenance, and testing procedures are the only reliable guide in any specific instance and, therefore, they should be consulted before undertaking any work on electrical equipment. The contents of this book do not represent a U.S. Nuclear Regulatory Commission (USNRC) position on the subjects covered in the book.

v

DK4058_C000.indd v

11/20/2008 10:17:57 AM

DK4058_C000.indd vi

11/20/2008 10:17:57 AM

Dedication In memory of my parents—Jasbir Singh and Amar Kaur To my wife Patricia—for her patience and understanding to make this work possible To my children/spouses—Shaun/Debra, Rajan/Larie, Jason/Deanna, and Rania/Alden and to my beautiful grandchildren Collin, Andrew, Ryan, Timothy, Owen, Henry, Jack, Maya, Chani, Paul, and Lauryn who keep me young and bring boundless joy to my journey in life

DK4058_C000.indd vii

11/20/2008 10:17:57 AM

DK4058_C000.indd viii

11/20/2008 10:17:57 AM

Contents Series Introduction ..................................................................................xxix Foreword .................................................................................................xxxi Preface .................................................................................................. xxxiii Acknowledgments .............................................................................. xxxvii Chapter 1

Maintenance Strategies, Dielectric Theory, Insulating Materials, Failure Modes, and Maintenance Impact on Arc-Flash Hazards 1.1 Introduction ...........................................................................................1 1.2 Why Maintain and Test .......................................................................1 1.3 Overview of Electrical Maintenance and Testing Strategies .........2 1.3.1 Key Factors in EPM Optimization Decisions ...................... 12 1.3.2 General Criteria for an Effective EPM and Testing Program............................................................... 12 1.3.3 Qualifications of EPM Personnel .......................................... 13 1.3.4 Optimization of PM Intervals ............................................... 14 1.3.5 Trending of Test Results......................................................... 15 1.3.6 Systematic Failure Analysis Approach ................................ 15 1.3.6.1 Postmaintenance Testing ......................................... 16 1.3.6.2 Engineering Support ................................................ 16 1.3.6.3 Summary.................................................................... 17 1.4 Planning an EPM Program ............................................................... 18 1.4.1 Maintenance Management Considerations......................... 18 1.4.1.1 Responsibilities .......................................................... 19 1.4.1.2 Inspection ................................................................... 19 1.4.1.3 Scheduling.................................................................. 19 1.4.1.4 Work Orders ............................................................... 20 1.4.1.5 Record Keeping ......................................................... 20 1.4.2 Technical Requirements ......................................................... 20 1.4.2.1 Survey of Plant Equipment ...................................... 20 1.4.2.2 Listing of Plant Equipment in the Order of Critical Importance .............................................. 23 1.4.2.3 Plan to Perform EPM on Regular Frequency........ 24 1.4.2.4 Development of Instruction and Procedures for the EPM Program................................................ 24 1.4.3 What Should Be Included in the EPM Program ................. 25 1.4.3.1 EPM and Testing ....................................................... 25 1.4.3.2 Electrical Repairs ...................................................... 25 1.4.3.3 Analysis of Failures .................................................. 25 1.4.3.4 Trending of Maintenance and Testing Data......... 26 1.4.3.5 Computerized Maintenance Management System ................................................ 26 ix

DK4058_C000.indd ix

11/20/2008 10:17:57 AM

x

Contents 1.5 Overview of Testing and Test Methods .......................................... 28 1.5.1 Types of Tests ........................................................................... 28 1.5.1.1 Acceptance Tests ........................................................ 28 1.5.1.2 Routine Maintenance Tests ...................................... 28 1.5.1.3 Special Maintenance Tests ....................................... 29 1.5.2 Types of Testing Methods ...................................................... 29 1.5.2.1 Solid Insulation Testing ........................................... 29 1.5.2.2 Insulating Liquid Testing ........................................ 30 1.5.2.3 Protective Device Testing ........................................30 1.5.2.4 Circuit Breaker Time–Travel Analysis ................... 31 1.5.2.5 Grounding Electrode Resistance Testing ..................................................... 31 1.5.2.6 Fault Gas Analysis Testing ...................................... 31 1.5.2.7 Infrared Inspection Testing ..................................... 32 1.6 Review of Dielectric Theory and Practice ....................................... 32 1.6.1 Characteristics of Dielectrics (Insulation) ...........................34 1.6.1.1 Dielectric Loss ............................................................ 35 1.6.1.2 PF and DF ................................................................... 35 1.6.1.3 Capacitance ................................................................ 35 1.6.2 Insulation as a Capacitor........................................................ 36 1.6.3 DC Voltage versus AC Voltage Tests .................................... 37 1.6.3.1 DC Voltage Tests........................................................ 38 1.6.3.2 AC Voltage Tests ........................................................ 38 1.6.4 Insulation Breakdown Modes ............................................... 39 1.7 Insulating Materials for Electrical Power Equipment ................................................................................ 40 1.7.1 Rigid Laminates Sheet, Rod, and Tube................................. 41 1.7.2 Glass Polyester Products ........................................................ 41 1.7.3 Flexible Laminates and Films ................................................ 41 1.7.4 Insulation Temperature Ratings ............................................ 46 1.8 Causes of Insulation Degradation and Failure Modes of Electrical Equipment ..................................................................... 47 1.8.1 Failure Modes—Electrical Power Equipment ..................... 51 1.8.1.1 Transformers .............................................................. 51 1.8.1.2 Switchgear and Circuit Breakers ............................ 56 1.8.1.3 Relays ..........................................................................64 1.8.1.4 Switchgear Buses .......................................................65 1.8.1.5 Cables and Connectors ............................................. 69 1.8.1.6 Rotating Machines .................................................... 71 1.9 Maintenance of Protective Devices and their Impact on Arc-Flash Hazard Analysis ......................................................... 81 1.9.1 Bases of Maintenance and Testing of Protective Devices ............................................................... 81 1.9.2 Failure Statistics ....................................................................... 91 1.9.3 Flash Hazard Analysis ........................................................... 92

DK4058_C000.indd x

11/20/2008 10:17:57 AM

Contents

xi

Chapter 2 2.1 2.2

2.3

2.4

2.5

2.6

2.7

2.8

DK4058_C000.indd xi

Direct-Current Voltage Testing of Electrical Equipment Introduction ......................................................................................... 97 DC Voltage Testing of Insulation ..................................................... 98 2.2.1 Dielectric Phenomena and Polarization ............................ 100 2.2.2 Advantages and Disadvantages of DC Voltage Testing ...................................................................... 101 2.2.2.1 Advantages.............................................................. 101 2.2.2.2 Disadvantages ........................................................ 102 DC Testing Methods ........................................................................ 102 2.3.1 Insulation Resistance Testing .............................................. 102 2.3.1.1 Short-Time Readings .............................................. 103 2.3.1.2 Time–Resistance Readings .................................... 103 2.3.1.3 PI Test ....................................................................... 105 2.3.1.4 Step-Voltage Readings (DC Voltage Tip-Up Test) ....................................... 105 2.3.2 High-Potential Voltage Test ................................................. 105 Transformers ..................................................................................... 106 2.4.1 Insulation Resistance Measurement .................................. 106 2.4.2 Dielectric Absorption Test ................................................... 110 2.4.3 DC High-Potential Test ........................................................ 111 Cables and Accessories .................................................................... 113 2.5.1 Insulation Resistance Measurement Test .......................... 113 2.5.2 DC Overpotential Testing.................................................... 117 2.5.3 Voltage versus Leakage Current Test (Step-Voltage Test).................................................................. 119 2.5.4 Leakage Current versus Time Test ..................................... 121 2.5.5 Go, No-Go Overpotential Test ............................................ 121 2.5.6 DC Overpotential Test Connections and Procedures ..... 121 Electrical Switchgear and Circuit Breakers .................................. 124 2.6.1 Insulation Resistance Measurement Test .......................... 124 2.6.2 DC High-Potential Test ........................................................ 126 2.6.3 Circuit Breaker Contact Resistance Measurement Test... 127 Motors and Generators .................................................................... 127 2.7.1 Insulation Resistance Test .................................................... 128 2.7.1.1 Field-Winding Test Procedures ............................. 128 2.7.1.2 Overall Stator (Armature Windings) Test ........... 129 2.7.1.3 Overall System Test for the Motor or Generator................................................. 130 2.7.1.4 Individual Stator Winding Test............................. 130 2.7.2 DC Overpotential Test .......................................................... 133 2.7.3 Voltage versus Leakage Current Test (Step-Voltage Test).................................................................. 133 2.7.4 Leakage Current versus Time Test ..................................... 134 Lightning Arresters .......................................................................... 136

11/20/2008 10:17:57 AM

Contents

xii 2.9

Capacitors ........................................................................................ 137 2.9.1 Tests to Check the Condition of New Capacitor Units before Placing in Service ....................................... 137 2.9.2 Tests to Check the Condition of a Capacitor Unit after It Has Been in Service ............................................. 137 2.10 Evaluation of Test Data Readings ................................................. 139 2.10.1 Acceptance Criteria for Rating Insulation ..................... 140 2.11 Precautions When Making DC Tests ........................................... 143

Chapter 3 Power Factor and Dissipation Factor Testing Methods 3.1 Introduction ..................................................................................... 145 3.2 PF and DF Test Methods................................................................ 146 3.2.1 General ................................................................................ 146 3.2.2 Principles of PF/DF Testing ............................................. 147 3.2.3 Factors That Influence PF Measurements ...................... 148 3.3 Description of the PF Test Equipment ......................................... 149 3.3.1 PF and DF Test Set ............................................................. 149 3.3.2 General Instructions for the Operation of the Megger Test Set ....................................................... 152 3.3.3 Doble PF Test Set ............................................................... 153 3.3.4 Operation of Doble PF Test Set ........................................ 153 3.4 Basic Test Connections (Test Modes) for PF Testing .................. 154 3.4.1 Grounded-Specimen Test Mode ...................................... 154 3.4.2 GST Mode with Guard (GST-G) ...................................... 154 3.4.3 Ungrounded-Specimen Test Mode ................................. 155 3.5 Safety Cautions with PF Testing .................................................. 155...