1791_TitlePage 7/9/03 2:45 PM Page 1 CRC PRESS Boca Raton London New York Washington, D.C. ElECTRIC POWER distribution handbook T.A. Short (C) 2004 by CRC Press LLC Electric Pwr Eng Series 7/9/03 4:10 PM Page 1 The ELECTRIC POWER ENGINEERING Series series editor Leo Grigsy Published Titles Computational Methods for Electric Power Systems Mariesa Crow Distribution System Modeling and Analysis William H. Kersting Electric Drives Ion Boldea and Syed Nasar Electrical Energy Systems Mohamed E. El-Hawary Electric Power Substations Engineering John D. McDonald Electric Power Transformer Engineering James H. Harlow Electromechanical Systems, Electric Machines, and Applied Mechatronics Sergey E. Lyshevski The Induction Machine Handbook Ion Boldea and Syed Nasar Linear Synchronous Motors: Transportation and Automation Systems Jacek Gieras and Jerry Piech Power Quality C. Sankaran Power System Operations and Electricity Markets Fred I. Denny and David E. Dismukes Electric Power Distribution Handbook Tom Short Forthcoming Titles The Electric Generators Handbook Ion Boldea The ELECTRIC POWER ENGINEERING Series Series Editor Leo L. Grigsby (C) 2004 by CRC Press LLC This book contains information obtained from authentic and highly regarded sources. Reprinted material is quoted with permission, and sources are indicated. A wide variety of references are listed. Reasonable efforts have been made to publish reliable data and information, but the author and the publisher cannot assume responsibility for the validity of all materials or for the consequences of their use. Neither this book nor any part may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, microfilming, and recording, or by any information storage or retrieval system, without prior permission in writing from the publisher. The consent of CRC Press LLC does not extend to copying for general distribution, for promotion, for creating new works, or for resale. Specific permission must be obtained in writing from CRC Press LLC for such copying. Direct all inquiries to CRC Press LLC, 2000 N.W. Corporate Blvd., Boca Raton, Florida 33431. Trademark Notice: Product or corporate names may be trademarks or registered trademarks, and are used only for identification and explanation, without intent to infringe. Visit the CRC Press Web site at www.crcpress.com © 2004 by CRC Press LLC No claim to original U.S. Government works International Standard Book Number 0-8493-1791-6 Library of Congress Card Number 2003055214 Printed in the United States of America 1 2 3 4 5 6 7 8 9 0 Printed on acid-free paper Library of Congress Cataloging-in-Publication Data Short, Tom, 1966– Electric power distribution handbook / Tom Short. p. cm. — (Electric power engineering series) Includes bibliographical references and index. ISBN 0-8493-1791-6 (alk. paper) 1. Electric power distribution—Handbooks, manuals, etc. I. Title. II. Series. TK3001.S47 2003 621.319—dc21 2003055214 1791_book.fm Page 4 Monday, August 4, 2003 3:20 PM (C) 2004 by CRC Press LLC Dedication To the future. To Jared. To Logan. 1791_book.fm Page 5 Monday, August 4, 2003 3:20 PM (C) 2004 by CRC Press LLC Preface In industrialized countries, distribution systems deliver electricity literally everywhere, taking power generated at many locations and delivering it to end users. Generation, transmission, and distribution — of these big three components of the electricity infrastructure, the distribution system gets the least attention. Yet, it is often the most critical component in terms of its effect on reliability and quality of service, cost of electricity, and aesthetic (mainly visual) impacts on society. Like much of the electric utility industry, several political, economic, and technical changes are pressuring the way distribution systems are built and operated. Deregulation has increased pressures on electric power utilities to cut costs and has focused emphasis on reliability and quality of electric service. The great fear of deregulation is that service will suffer because of cost cutting. Regulators and utility consumers are paying considerable atten- tion to reliability and quality. Another change that is brewing is the intro- duction of distributed generation on the distribution system. Generators at the distribution level can cause problems (and have benefits if properly applied). Customers are pressing for lower costs, better reliability, and less visual impact from utility distribution systems. Deregulation and technical changes increase the need by utility engi- neers for better information. This book helps fill some of those needs in the area of electric distribution systems. The first few chapters of the book focus on equipment-oriented information and applications such as choos- ing transformer connections, sizing and placing capacitors, and setting regulators. The middle portion of this handbook contains many sections targeting reliability and power quality. The performance of the distribution system determines greater than 90% of the reliability of service to customers (the high-voltage transmission and generation system determines the rest). If performance is increased, it will have to be done on the distribution system. Near the end, we tackle lightning protection, grounding, and safety. Safety is a very important consideration in the design, operation, and maintenance of distribution facilities. The last chapter on distributed generation provides information to help utilities avoid problems caused by the introduction of distributed generation. I hope you find useful information in this book. If it is not in here, hopefully one of the many bibliographic references will lead you to what you are looking for. Please feel free to email me feedback on this book including errors, comments, opinions, or new sources of information. I would like to 1791_book.fm Page 7 Monday, August 4, 2003 3:20 PM (C) 2004 by CRC Press LLC hear from you. Also, if you need my help with any interesting consulting or research opportunities, I would love to hear from you. Tom Short EPRI PEAC Schenectady, New York t.short@ieee.org 1791_book.fm Page 8 Monday, August 4, 2003 3:20 PM (C) 2004 by CRC Press LLC Foreword The public profile of electricity and those who provide it is likely to dramatically increase. Unlike the industrial analog economy of the 20th century, the net- worked digital economy only runs on electricity — that is, a perfect stream of electrons seamlessly linked with a real-time flow of information. Productivity and competitive advantage depend on rapidly facilitating this transformation. The challenges of the digital economy come at a time of rapid change for the electric power industry and especially for its power delivery system. Meanwhile, many areas are now considering ways to increase competition in retail markets and provide customers with greater choice among electricity providers. The capability of the power delivery system, however, has not kept up with the new demands brought by deregulation. Most transmission and distribution systems were designed more than a half-century ago, when long-distance power transfer was used mainly for economic exchange among a few utilities and when the reliability requirements of distribution systems were much less severe than in a digital economy. So far, the needed improvements in both capacity and reliability have not been made. While utility loads have grown and users are more demanding, the dis- tribution infrastructure has not kept pace. Consider the period from 1989 to 1999 when total electricity demand in the U.S. rose by nearly 30% — over the same period, expenditures by investor-owned utilities for distribution system construction fell by about 10% in real terms (based on data from EEI’s Statistical Yearbook , 1999). Mr. Short’s handbook provides many tools to help address the challenges of providing a more reliable distribution system given significant cost con- straints. In addition to a wealth of classic information on distribution prac- tices, his handbook provides new insights based on recent research by EPRI, the Consortium for Electric Infrastructure to Support a Digital Society (CEIDS), IEEE, and others. As someone who started his utility career as an electrician, I appreciate the practical advice provided by this handbook. While the book has leading- edge research and a great deal of in-depth technical information, it also manages to offer considerable practical information. As a former practitioner, I also appreciate the handbook’s consideration of issues affecting safety. This handbook is a fine addition to CRC Press’s Electric Power Engineering Series, which distribution engineers should find useful for many years. Clark W. Gellings, PE Vice President — Power Delivery and Markets EPRI Palo Alto, California 1791_book.fm Page 9 Monday, August 4, 2003 3:20 PM (C) 2004 by CRC Press LLC Acknowledgments First and foremost, I would like to thank my wife Kristin — thank you for your strength, thank you for your help, thank you for your patience, and thank you for your love. My play buddies, Logan and Jared, energized me and made me laugh. My family was a source of inspiration. I would like to thank my parents, Bob and Sandy, for their influence and education over the years. EPRI PEAC provided a great deal of support on this project. I would like to recognize the reviews, ideas, and support of Phil Barker and Dave Crudele here in Schenectady, New York, and also Arshad Mansoor, Mike Howard, Charles Perry, Arindam Maitra, and the rest of the energetic crew in Knox- ville, TN. Many other people reviewed portions of the draft and provided input and suggestions, including Dave Smith (Power Technologies, Inc.), Dan Ward (Dominion Virginia Power), Jim Stewart (Consultant, Scotia, NY), Conrad St. Pierre (Electric Power Consultants), Karl Fender (Cooper Power Sys- tems), John Leach (Hi-Tech Fuses, Inc.), and Rusty Bascom (Power Delivery Consultants). Thanks to Power Technologies, Inc., for opportunities and mentoring dur- ing my early career with the help of several talented, helpful engineers, including Jim Burke, Phil Barker, Dave Smith, Jim Stewart, and John Ander- son. Over the years, several clients have also educated me in many ways; two that stand out are Ron Ammon (Keyspan, retired) and Clay Burns (National Grid). EPRI has been supportive of this project, including a review by Luther Dow. EPRI has also sponsored a number of interesting distribution research projects that I have been fortunate enough to be involved with, and EPRI has allowed me to share some of those efforts here. As a side-note, I would like to recognize the efforts of linemen in the electric power industry. These folks do the real work of building the lines and keeping the power on. As a tribute to them, a trailer at the end of each chapter reveals a bit of the lineman’s character and point of view. 1791_book.fm Page 11 Monday, August 4, 2003 3:20 PM (C) 2004 by CRC Press LLC Credits Tables 4.3 to 4.7 and 4.13 are reprinted with permission from IEEE Std. C57.12.00-2000. IEEE Standard General Requirements for Liquid-Immersed Dis- tribution, Power, and Regulating Transformers. Copyright 2000 by IEEE. Figure 4.17 is reprinted with permission from ANSI/IEEE Std. C57.105- 1978. IEEE Guide for Application of Transformer Connections in Three-Phase Distribution Systems. Copyright 1978 by IEEE. Tables 6.2, 6.4, and 6.5 are reprinted with permission from IEEE Std. 18- 2002. IEEE Standard for Shunt Power Capacitors. Copyright 2002 by IEEE. Table 6.3 is reprinted with permission from ANSI/IEEE Std. 18-1992. IEEE Standard for Shunt Power Capacitors. Copyright 1993 by IEEE. Table 7.9 is reprinted with permission from IEEE Std. 493-1997. IEEE Rec- ommended Practice for the Design of Reliable Industrial and Commercial Power Systems (Gold Book). Copyright 1998 by IEEE. Table 8.3 is reprinted with permission from IEEE Std. C37.112-1996. IEEE Standard Inverse-Time Characteristic Equations for Overcurrent Relays. Copy- right 1997 by IEEE. Tables 11.1 to 11.3 are reprinted with permission from IEEE Std. 519-1992. IEEE Recommended Practices and Requirements for Harmonic Control in Electrical Power Systems. Copyright 1993 by IEEE. Figure 11.19 is reprinted with permission from IEEE Std. 141-1993. IEEE Recommended Practice for Electric Power Distribution for Industrial Plants. Copy- right 1994 by IEEE. Tables 12.4 and 12.5 are reprinted with permission from IEEE Std. C62.22- 1997. IEEE Guide for the Application of Metal-Oxide Surge Arresters for Alter- nating-Current Systems. Copyright 1998 by IEEE. Figure 12.16 is reprinted with permission from IEEE Std. 4-1995. IEEE Standard Techniques for High-Voltage Testing. Copyright 1995 by IEEE. Figure 12.19 is reprinted with permission from IEEE Std. 1299/C62.22.1- 1996. IEEE Guide for the Connection of Surge Arresters to Protect Insulated, Shielded Electric Power Cable Systems. Copyright 1997 by IEEE. Section 12.7.2.1 is reprinted with permission from IEEE Std. 1410-1997. IEEE Guide for Improving the Lightning Performance of Electric Power Overhead Distribution Lines . Copyright 1997 by IEEE. Tables 13.3 and 13.4 are reprinted with permission from IEEE Std. 142- 1991. IEEE Recommended Practice for Grounding of Industrial and Commercial Power Systems. Copyright 1992 by IEEE. Figure 13.15 is reprinted with permission from IEEE Std. 80-2000. IEEE Guide for Safety in AC Substation Grounding . Copyright 2000 by IEEE. The IEEE disclaims any responsibility or liability resulting from the place- ment and use in the described manner. 1791_book.fm Page 13 Monday, August 4, 2003 3:20 PM (C) 2004 by CRC Press LLC Contents 1 Fundamentals of Distribution Systems 1.1 Primary Distribution Configurations 1.2 Urban Networks 1.3 Primary Voltage Levels 1.4 Distribution Substations 1.5 Subtransmission Systems 1.6 Differences between European and North American Systems 1.7 Loads 1.8 The Past and the Future References 2 Overhead Lines 2.1 Typical Constructions 2.2 Conductor Data 2.3 Line Impedances 2.4 Simplified Line Impedance Calculations 2.5 Line Impedance Tables 2.6 Conductor Sizing 2.7 Ampacities 2.7.1 Neutral Conductor Sizing 2.8 Secondaries 2.9 Fault Withstand Capability 2.9.1 Conductor Annealing 2.9.2 Burndowns 2.10 Other Overhead Issues 2.10.1 Connectors and Splices 2.10.2 Radio Frequency Interference References 3 Underground Distribution 3.1 Applications 3.1.1 Underground Residential Distribution (URD) 3.1.2 Main Feeders 3.1.3 Urban Systems 3.1.4 Overhead vs. Underground 3.2 Cables 3.2.1 Cable Insulation 3.2.2 Conductors 1791_book.fm Page 15 Monday, August 4, 2003 3:20 PM (C) 2004 by CRC Press LLC [...]... some material that should help distribution planners, many of the tasks of a planner, like load forecasting, are not discussed For more information on distribution planning, see Willis’s Power Distribution Planning Reference Book (1997), IEEE’s Power Distribution Planning tutorial (1992), and the CEA Distribution Planner’s Manual (1982) 1.1 Primary Distribution Configurations Distribution circuits come... luxury — now a necessity — electricity powers the machinery, the computers, the health-care systems, and the entertainment of modern society Given its benefits, electricity is inexpensive, and its price continues to slowly decline (after adjusting for inflation — see Figure 1.1) Electric power distribution is the portion of the power delivery infrastructure that takes the electricity from the highly... transformer or Network protector 208Y/120 V or 480Y/277 V spot network FIGURE 1.9 Spot network (Copyright © 2000 Electric Power Research Institute 1000419 Engineering Guide for Integration of Distributed Generation and Storage Into Power Distribution Systems Reprinted with permission.) C57.12.44–2000) A network protector senses and operates for reverse power flow (it does not have forward-looking protection)... Some also think of distribution as anything that is radial or anything that is below 35 kV The distribution infrastructure is extensive; after all, electricity has to be delivered to customers concentrated in cities, customers in the suburbs, and customers in very remote regions; few places in the industrialized world do not have electricity from a distribution system readily available Distribution circuits... Peak current Peak load Power factor Number of customers Length of feeder mains Length including laterals Area covered Mains wire size Lateral tap wire size Lateral tap peak current Lateral tap length Distribution transformer size (1 ph) Copyright © 2000 Electric Power Research Institute 1000419 Engineering Guide for Integration of Distributed Generation and Storage Into Power Distribution Systems Reprinted... N.C N.C N.O N.C FIGURE 1.6 Primary loop distribution arrangement (Copyright © 2000 Electric Power Research Institute 1000419 Engineering Guide for Integration of Distributed Generation and Storage Into Power Distribution Systems Reprinted with permission.) sensing a loss of voltage It normally has a time delay on the order of seconds — enough to ride through the distribution circuit’s normal reclosing... of the electricity infrastructure TABLE 1.1 Surveyed Annual Utility Distribution Budgets in U.S Dollars Average Per Per Per Per Per dollar of distribution asset customer thousand kWH mile of circuit substation Range 0.098 195 8.9 9,400 880,000 0.0916–0.15 147–237 3.9–14.1 4,800–15,200 620,000–1,250,000 Source: EPRI TR-109178, Distribution Cost Structure — Methodology and Generic Data, Electric Power. .. conductors on a higher voltage system or carry more power on the same size conductor Utilities can run much longer distribution circuits at a higher primary voltage, which means fewer distribution substations Some fundamental relationships are: • Power — For the same current, power changes linearly with voltage P2 = V1 P V1 1 when I2 = I1 • Current — For the same power, increasing the voltage decreases current... K fuse 100 K fuse R Recloser Three-phase mains Normally open tie FIGURE 1.3 Typical distribution substation with one of several feeders shown (many lateral taps are left off) (Copyright © 2000 Electric Power Research Institute 1000419 Engineering Guide for Integration of Distributed Generation and Storage Into Power Distribution Systems Reprinted with permission.) (C) 2004 by CRC Press LLC (C) 2004... deregulation, the distribution infrastructure remains a natural monopoly As with water delivery or sewers or other utilities, it is difficult to imagine duplicating systems to provide true competition, so it will likely remain highly regulated Because of the extensive infrastructure, distribution systems are capitalintensive businesses An Electric Power Research Institute (EPRI) survey found that the distribution . Markets Fred I. Denny and David E. Dismukes Electric Power Distribution Handbook Tom Short Forthcoming Titles The Electric Generators Handbook Ion Boldea The ELECTRIC POWER ENGINEERING Series Series Editor. 1966– Electric power distribution handbook / Tom Short. p. cm. — (Electric power engineering series) Includes bibliographical references and index. ISBN 0-8493-1791-6 (alk. paper) 1. Electric power. London New York Washington, D.C. ElECTRIC POWER distribution handbook T.A. Short (C) 2004 by CRC Press LLC Electric Pwr Eng Series 7/9/03 4:10 PM Page 1 The ELECTRIC POWER ENGINEERING Series series