Practical Grounding Bonding Shielding

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<p>Practical Grounding, Bonding, Shielding and Surge Protection</p> <p>ii</p> <p>Contents</p> <p>Other titles in the series Practical Data Acquisition for Instrumentation and Control Systems (John Park, Steve Mackay) Practical Data Communications for Instrumentation and Control (Steve Mackay, Edwin Wright, John Park) Practical Digital Signal Processing for Engineers and Technicians (Edmund Lai) Practical Electrical Network Automation and Communication Systems (Cobus Strauss) Practical Embedded Controllers (John Park) Practical Fiber Optics (David Bailey, Edwin Wright) Practical Industrial Data Networks: Design, Installation and Troubleshooting (Steve Mackay, Edwin Wright, John Park, Deon Reynders) Practical Industrial Safety, Risk Assessment and Shutdown Systems for Instrumentation and Control (Dave Macdonald) Practical Modern SCADA Protocols: DNP3, 60870.5 and Related Systems (Gordon Clarke, Deon Reynders) Practical Radio Engineering and Telemetry for Industry (David Bailey) Practical SCADA for Industry (David Bailey, Edwin Wright) Practical TCP/IP and Ethernet Networking (Deon Reynders, Edwin Wright) Practical Variable Speed Drives and Power Electronics (Malcolm Barnes) Practical Centrifugal Pumps (Paresh Girdhar and Octo Moniz) Practical Electrical Equipment and Installations in Hazardous Areas (Geoffrey Bottrill and G. Vijayaraghavan) Practical E-Manufacturing and Supply Chain Management (Gerhard Greef and Ranjan Ghoshal) Practical Hazops, Trips and Alarms (David Macdonald) Practical Industrial Data Communications: Best Practice Techniques (Deon Reynders, Steve Mackay and Edwin Wright) Practical Machinery Safety (David Macdonald) Practical Machinery Vibration Analysis and Predictive Maintenance (Cornelius Scheffer and Paresh Girdhar) Practical Power Distribution for Industry (Jan de Kock and Cobus Strauss) Practical Process Control for Engineers and Technicians (Wolfgang Altmann) Practical Telecommunications and Wireless Communications (Edwin Wright and Deon Reynders) Practical Troubleshooting Electrical Equipment (Mark Brown, Jawahar Rawtani and Dinesh Patil)</p> <p>Contents</p> <p>iii</p> <p>Practical Grounding, Bonding, Shielding and Surge ProtectionG. Vijayaraghavan, B.Eng (Hons) Consulting Engineer, Chennai, India Mark Brown, Pr.Eng, DipEE, B.Sc (Elec.Eng), Senior Staff Engineer, IDC Technologies, Perth, Australia. Malcolm Barnes, CPEng, BSc (ElecEng), MSEE, Alliance Automation, Perth,Western Australia</p> <p>Series editor: Steve Mackay</p> <p>AMSTERDAM BOSTON HEIDELBERG LONDON NEW YORK OXFORD PARIS SAN DIEGO SAN FRANCISCO SINGAPORE SYDNEY TOKYONewnes is an imprint of Elsevier</p> <p>iv</p> <p>Contents</p> <p>Newnes An imprint of Elsevier Linacre House, Jordan Hill, Oxford OX2 8DP 200 Wheeler Road, Burlington, MA 01803 First published 2004 Copyright 2004, IDC Technologies. All rights reservedNo part of this publication may be reproduced in any material form (including photocopying or storing in any medium by electronic means and whether or not transiently or incidentally to some other use of this publication) without the written permission of the copyright holder except in accordance with the provisions of the Copyright, Designs and Patents Act 1988 or under the terms of a licence issued by the Copyright Licensing Agency Ltd, 90 Tottenham Court Road, London, England WIT 4LP. Applications for the copyright holders written permission to reproduce any part of this publication should be addressed to the publisher Permissions may be sought directly from Elseviers Science and Technology Rights Department in Oxford, UK: phone: (+44) (0) 1865 843830; fax: (+44) (0) 1865 853333; e-mail: permissions@elsevier.co.uk. You may also complete your request on-line via the Elsevier homepage (http://www.elsevier.com), by selecting Customer Support and then Obtaining Permissions British Library Cataloguing in Publication Data Vijayaraghavan, G. Practical grounding, bonding, shielding and surge protection. (Practical professional) 1. Electric apparatus and appliances Protection 2. Electric currents Grounding I. Title 621. 317 Library of Congress Cataloguing in Publication Data A catalogue record for this book is available from the Library of Congress</p> <p>ISBN</p> <p>0 7506 6399 5</p> <p>For information on all Newnes publications visit our website at www.newnespress.com</p> <p>Typeset and edited by Integra Software Services Pvt. Ltd, Pondicherry, India www.integra-india.com Printed and bound in The Netherlands</p> <p>Working together to grow libraries in developing countrieswww.elsevier.com | www.bookaid.org | www.sabre.org</p> <p>Contents</p> <p>v</p> <p>Contents</p> <p>Preface ............................................................................................................................ ix 1 Introduction and basics .........................................................................................1 1.1 Introduction...............................................................................................1 1.2 Basics of grounding ..................................................................................2 1.3 Bonding ....................................................................................................4 1.4 Lightning and its effect on electrical systems............................................4 1.5 Static charges and the need for bonding ..................................................5 1.6 Ground electrodes and factors affecting their efficacy ..............................6 1.7 Noise in signaling circuits and protective measures such as shielding .....8 1.8 Surge protection of electronic equipment .................................................9 1.9 UPS systems and their role in power quality improvement .....................10 1.10 Case studies...........................................................................................11 1.11 Importance of local codes.......................................................................11 1.12 Summary ................................................................................................11 Grounding of power supply system neutral..........................................................13 2.1 Introduction.............................................................................................13 2.2 Ungrounded systems..............................................................................15 2.3 Solidly grounded systems.......................................................................16 2.4 Impedance grounding using neutral reactor ...........................................18 2.5 Resonant grounding using neutral reactor ..............................................18 2.6 Impedance grounding through neutral resistance...................................19 2.7 Point of grounding ..................................................................................20 2.8 Other challenges ....................................................................................21 2.9 Summary ................................................................................................23 Equipment grounding ..........................................................................................24 3.1 Introduction.............................................................................................24 3.2 Shock hazard .........................................................................................24 3.3 Grounding of equipment .........................................................................27 3.4 Operation of protective devices ..............................................................28 3.5 Thermal capability ..................................................................................29 3.6 Touch Potential during ground faults ......................................................30 3.7 Induced voltage problem ........................................................................30 3.8 Mitigation by multiple ground connection................................................31 3.9 Mitigation by reduction of conductor spacing ..........................................31</p> <p>2</p> <p>3</p> <p>vi</p> <p>Contents</p> <p>3.10 3.11 3.12 3.13 3.14 3.15 4</p> <p>EMI suppression .................................................................................... 32 Metal enclosures for grounding conductors ........................................... 32 Grounding connections for surge protection equipment ......................... 34 Sensing of ground faults ........................................................................ 34 Equipotential bonding ............................................................................ 35 Summary ............................................................................................... 37</p> <p>Lightning, its effect on buildings and electrical systems and protection against lightning.................................................................................................. 38 4.1 Introduction ............................................................................................ 38 4.2 Incidence of lightning ............................................................................. 41 4.3 Probability of lightning strike .................................................................. 45 4.4 Method of lightning protection ................................................................ 47 4.5 Planning for lightning protection............................................................. 50 4.6 Improvements to lightning protection ..................................................... 51 4.7 Factors governing decision whether or not to protect............................. 52 4.8 Effect of lightning strike on electrical lines.............................................. 53 4.9 Summary ............................................................................................... 54 Static electricity and protection ........................................................................... 55 5.1 Introduction ............................................................................................ 55 5.2 What is static electricity?........................................................................ 55 5.3 Generation of charge ............................................................................. 56 5.4 Some common examples of static buildup............................................. 56 5.5 Energy of spark and its ignition capability .............................................. 57 5.6 Dangers of static electricity buildup........................................................ 58 5.7 Control of static electricity ...................................................................... 58 5.8 Assessment of static risks and planning prevention............................... 61 5.9 Summary ............................................................................................... 61 Ground electrode system.................................................................................... 62 6.1 Introduction ............................................................................................ 62 6.2 Grounding electrodes............................................................................. 62 6.3 Soil resistance ....................................................................................... 63 6.4 Measurement of soil resistivity ............................................................... 64 6.5 Resistance of a single rod electrode ...................................................... 68 6.6 Current-carrying capacity of an electrode .............................................. 70 6.7 Use of multiple ground rods in parallel ................................................... 71 6.8 Measurement of ground resistance of an electrode ............................... 71 6.9 Concrete-encased electrodes ................................................................ 73 6.10 Corrosion problems in electrical grounding systems .............................. 75 6.11 Maintenance of grounding system ......................................................... 76 6.12 Chemical electrodes .............................................................................. 76 6.13 Summary ............................................................................................... 78 Surge protection of electronic equipment............................................................ 79 7.1 Introduction ............................................................................................ 79 7.2 What is a surge? .................................................................................... 79</p> <p>5</p> <p>6</p> <p>7</p> <p>Contents</p> <p>vii</p> <p>7.3 7.4 7.5 7.6 7.7 7.8 7.9 7.10 8</p> <p>Bonding of different ground systems as a means of surge proofing .......80 Surges and surge protection...................................................................82 Principle of surge protection ...................................................................85 Surge protection of electronic equipment ...............................................86 Achieving graded surge protection .........................................................88 Positioning and selection of lightning/surge arrestor...............................89 A practical view of surge protection for sensitive equipment...................92 Summary ..............................................................................................101</p> <p>Electrical noise and mitigation ...........................................................................102 8.1 Introduction...........................................................................................102 8.2 Definition of electrical noise and measures for noise reduction ............102 8.3 How are sensitive circuits affected by noise? .......................................105 8.4 Frequency analysis of noise .................................................................106 8.5 Categories of noise...............................................................................109 8.6 Disturbances from other equipment in the same distribution system ....110 8.7 Earth loop as a cause of noise .............................................................111 8.8 The ways in which noise can enter a signal cable and its control .........113 8.9 More about shielding ...........................................................................117 8.10 Shielded isolation transformer ..............................................................121 8.11 Avoidance of earth loop ........................................................................123 8.12 Use of insulated ground (IG) receptacle ..............................................125 8.13 Zero signal reference grid and signal transport ground plane ...............126 8.14 Harmonics in electrical systems ..........................................................128 8.15 Summary .............................................................</p>

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