EMC For Systems And Installations

327 Pages·2000·32.64 MB·English

by  Tim Williams

EMC for Systems
and Installations
This Page Intentiona Left Blank
EMC for Systems
and Installations
Tim Wi IH ams
&
Keith Armstrong
Newnes
OXFORD AUCKLAND BOSTON JOHANNESBURG MELBOURNE NEW DELHI
Newnes
An imprint of Butterworth-Heinemann
Linacre House, Jordan Hill, Oxford OX2 8DP
225 Wildwood Avenue, Woburn, MA 01801-2041
A division of Reed Educational and Professional Publishing Ltd
--~A member of the Reed Elsevier plc group
First published 2000
(cid:14)9 Reed Educational and Professional Publishing Ltd 2000
All rights reserved. No 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 W1P 0LP. Applications for the copyright holder's written
permission to reproduce any part of this publication should be addressed
to the publishers
British Library Cataloguing in Publication Data
A catalogue record for this book is available from the British Library
Library of Congress Cataloguing in Publication Data
A catalogue record for this book is available from the Library of Congress
ISBN 0 7506 4167 3
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Printed and Bound in Great Britain by
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Contents
Preface xi
Chapter 1
Introduction: the EMC needs of systems 1
The definition of electromagnetic compatibility 2
A description of EMC phenomena 3
The need for EMC 8
Control of emissions 8
Control of immunity 9
Safety aspects 11
Chapter 2
The EMC Directive's requirements for systems and installations 13
Introduction to the EMC Directive 13
Scope and purpose 14
Other CE marking directives 17
The meaning of the CE Mark 18
Applicability to systems and installations 20
The 1997 guidelines 2O
Definitions of systems and installations 26
The "responsible person" 27
The "instructions for use" 28
Routes to compliance 29
Self certification to standards 29
Using the Technical Construction File 31
Does "CE + CE = CE?" 34
The "Procedural Approach" to compliance 37
Enforcement and the future of the EMC Directive 38
The UK situation 38
Other countries 38
The SLIM initiative 4O
Chapter 3
Management of systems EMC 43
The EMC control plan 43
vi Contents
The EMC control board 43
Identifying EMC issues 44
Identifying and sourcing critical parts 47
Control of assembly and installation 48
The EMC test plan 49
Defining the configuration to be tested 49
Defining the tests to be done 50
Testing system modules 50
Testing the whole system 50
Documentation 52
Documentation for in-house use 52
Documentation for a TCF 52
Purchasing 52
Determining the EMC specifications for an incorporated item 53
Checking suppliers' evidence of EMC performance 56
Maintenance, upgrades and enhancements 62
Maintenance 62
The relevance of upgrades or enhancements 63
Training 64
Training and awareness check list 64
Chapter 4
Interference sources, victims and coupling 67
Phenomena in the electromagnetic environment 67
Examples of radiated field threats 76
Continuous radiated threats from radio transmitters 77
Coupling 78
Direct coupling 78
Near field (inductive and capacitive) coupling 81
Radiated coupling 84
The modes of coupling 86
Protection measures 89
Mains harmonics 92
Their causes and problems 92
Harmonic solutions 95
EMC versus safety 96
Filter problems 97
Screened enclosures 99
Chapter 5
Earthing and bonding 101
The concept and practice of earth 101
The purposes of the earth connection 101
Definitions of the EMC earth 103
Earthing techniques 106
The impedance of the earth connection 112
EMC for Systems and Installations vii
Impedance of wires 112
Effective bonding of joints 115
Creating the meshed facility earth 123
Constructing SRPPs and bonding mats for system blocks 123
Improving the earth-bonding of older buildings 126
Maintaining earth-bonding networks 131
Non-IT installations 131
Chapter 6
Cabinets, cubicles and chambers 133
The purpose of a metallic enclosure 133
Transfer impedance of the earth reference ]33
Layout and placement within the enclosure ]34
Shielding theory 137
Shielding effectiveness ]37
The effect of apertures, seams and penetrations ]4]
Shielding techniques 144
Bonding structural components ]44
Shielding hardware ]45
Installation and maintenance of screened enclosures ]51
Architectural shielding 151
Apertures ]52
Chapter 7
Cabling 155
Coupling to, from and within cables 155
Differential mode 155
Common mode 159
Crosstalk 163
Cable screening techniques 164
Options for cable screening 164
Cable transfer impedance 166
Terminating the screen 168
Which end to earth ? 171
Unscreened cables 175
Twisted pair 176
Ribbon cable 178
Installing cable systems 179
Cable classification 179
Segregation and routing 184
Parallel Earth Conductor (PEC) techniques 188
viii Contents
Chapter 8
Filtering 193
Attenuating noise at the interfaces 193
The low pass filter 193
Differential versus common mode in filters 194
Source and load impedances 195
Layout and installation 197
Mains filters 200
The operation of standard mains filters 2Ol
Extending the performance of standardfilters 202
Filtering other lines 205
Filtered connector adaptors 206
Using ferrites 207
Chapter 9
Lightning and surge protection 211
The EMC problems of lightning 211
How lightning phenomena can affect electronic apparatus 211
Overview of design of a lightning protection system (LPS) 213
Basic LPS design for safety and structural protection 214
Risk assessment 214
Construction of an LPS 215
Bonding external cables and metallic services to earth 219
Additional LPS measures to protect electronic apparatus 220
Enhancing the LPS structure 221
Protection of exposed equipment 221
Enhanced earthing and bonding 222
Cable routing and screen bonding 225
Use of isolation techniques and fibre-optics 226
Zoning and surge protection 226
Protecting from non-lightning surges 233
Chapter 10
In situ testing 235
Emissions 235
CISPR instrumentation and transducers 235
Conducted test methods 246
Radiated test methods 249
Practical aspects of in-situ emissions tests 253
Immunity 257
Practical aspects of immunity tests 257
Electrostatic discharge 257
Electrical fast transient bursts 261
Surges 264
Radiated and conducted RF 266
EMC for Systems and Installations ix
Aooendix A
Systems EMC procedures checklist 275
Company Procedures 275
Designers 275
Assemblers 276
User and Installation Manuals 276
Installation, commissioning, service 277
Aooendix B
Determining performance criteria 279
Aooendix C
Some published case studies 285
Segaworld 285
Air Traffic Services 286
VDU image problems in a steel rolling mill 289
Large explosion at the Texaco Refinery, Milford Haven, July 1994 290
Wide area interference created by large inverter drives 291
Release of chlorine gas in semiconductor processing plant 292
Traction current interference to safety circuits 292
Aooendix D
The EU and EEA countries 293
The European Union 293
The European Economic Area 293
Glossary 295
Bibliography 297
Index 307