Hans Gumhalter

Power Supply in Telecommunications

Springer Berlin Heidelberg New York Barcelona Budapest Hong Kong London Mailand Paris Tokyo

Hans Gumhalter

Power Supply in Telecol11l11unications

Third, Completely Revised Edition with 263 Figures and 45 Tables

" Springer

Hans Gumhalter SiemensAG HofmannstraBe 51 D-81359 Munchen Germany

ISBN-13 :978-3-642-78405-7 DOl: 10.1007/978-3-642-78403-3

e-ISBN -13 :978-3-642-78403-3

2nd edition: "Power Supply Systems in Communications Engineering" © Siemens Aktiengesellschaft and John Wiley and Sons 1986

Library of Congress Cataloging - in - Publication Data Gumhalter, Hans.

[Stromversorgungssysteme der Kommunikationstechnik. English] Power supply in telecommunications / Hans Gumhalter. - 3rd.

completely rev. ed. p. cm.

Includes bibliographical references and index. ISBN-13:978-3-642-78405-7 1. Telecommunication systems - Power supply. I. Title.

TK5102.5.G68513 1995 621.382'32--dc20

This work is subject to copyright. All rights are reserved, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in other ways, and storage in data banks. Duplication of this publication or parts thereof is only per­mitted under the provisions of the German Copyright Law of September 9, 1965, in its current version, and a copyright fee must always be paid. Violations fall under the prosecution act of the German Copyright law.

© Springer-Verlag Berlin Heidelberg 1995 Softcover reprint of the hardcover 3rd edition 1995

The use of registered names, trademark, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use.

Production: PRODUserv Springer Produktions-Gesellschaft, Berlin Typesetting: Macmillan India Ltd., Bangalore SPIN 10037229 6113020 - 543210 - Printed on acid-free paper.

This book is dedicated to the memory of my dear late father

Felix Gumhalter, born 6 January 1905

and deceased 30 December 1993, Retired Post and Telegraph Superintendent,

Vienna, Austria.

lowe him everything in my life. His works and his humanity will be remembered by all who knew him.

Hans Gumhalter

Preface

An important part of any communications system is its power supply system. The smooth running of all communications depends directly on the quality of the power supply and thus on the operational reliability of the ever more complex equipment and devices used for the purpose.

It is the intention of this book to explain present-day technology in the supply of power for telecommunications comprehensively and in detail with thyristor and transistor-controlled converters, as developed by manufacturers and applied by users, and explains the circuit techniques and relationships with the aid of extensive generally conceived illustrations. The book also deals with the subjects of automatic control, grounding (earthing) and protection tech­niques. Information is given on the planning to battery and earthing installa­tions.

The individual chapters are constructed and written so that the book will be useful for those readers seriously wishing to become involved in the subject as well as for those having to deal directly with the equipment such as in planning, installation, commissioning and servicing.

The selection of material and method of presentation are based on know­ledge and experience gained in the context of training measures for power supply systems.

Thanks are due especially to Dr. Dietrich Berndt for his energetically assistance with Chap. 6 and following companies for generous assistance and permission to use documentation, descriptions, operating instructions, circuit diagrams and photos: Gustav Klein GmbH & Co KG, Accumulatorenfabrik Sonnenschein GmbH, Stamford A.C. Generators Newage International Com­pany, AD. Striiver KG (GmbH & Co), Siemens AG, Varta AG, Hagen Batterie AG.

Munich, July 1995 Hans Gumhalter

Contents

1

1.1 1.2 1.3 1.4 1.5 1.6 1.6.1 1.6.2 1.6.3 1.6.4 1.7 1.8 1.9

2

2.1 2.1.1 2.1.2 2.1.3 2.1.4 2.1.5 2.1.6 2.1.7 2.2

3

General and Introduction . . . . . .

Functions and Requirements. . . . . . . . . . . ....... . Basic Types of Power Converter . . . . . . . . . . . . . . . . . . Elements of a Power Converter. . . . . . . . . . . . . . . . ... Energy Storage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . Primary Power Sources ....................... . Power Supply Systems . . . . . . . . . . . . . . . . . . . . . . . . Mains Supply and Standby Power Supply Systems . . . . . . . Mains Distribution Switchboards or Mains Switch Panels . . . Central Power Supply ........................ . Decentralized Power Supply. . . . . . . . . . . . . . . . . . . . . UPS Systems. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Mains-independent Hybrid Power Supply Systems. . . . . . . . Historical Review . . . . . . . . . . . . . . . . . . . . . . . . . . .

Requirements of Telecommunications Systems on the Power Supply. . . . . . . . . . . . . . . . . . .

D.C. Power Supplies . . . . . . . . . . . . . . . . . . . . . . .. . Level of the Direct Voltages .................... . Tolerance for Direct Voltages ................... . Purity of Direct Voltages. . . . . . . . . . . . . . . . . . . . . . . Filter Sections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Degree of Radio Interference and Limit Classes . . . . . . . . . Power Distribution System and Voltage Drops ......... . Availability of the Power Supply ................. . A.C. Power Supplies. • . . . . . . . . . . . . . . . . . . . . . . ..

Operating Modes of a Direct Current Power Supply System . . . . . . . . . . . . . . . . . .

1

2 3 4 5 6 7 9 9

10 12 14 15 16

20 20 20 20 24 26 28 28 29 31

32

3.1 Rectifier Mode. . . . . . . . . . . . . . . . . . . . . . . . . .. 32 3.2 Battery (Charge-Discharge) Mode. . . . . . . . . . . . 32 3.3 Standby Parallel Mode. . . . . . . . . . . . . . . . . . . . . . . . 32 3.3.1 Standby Parallel Mode with Reducing Diodes

(Counter electromotive Cells) . . . . . . . . . . . . . . . . . . .. 37 3.3.2 Standby Parallel Mode with d.c./d.c. Converter . . . . . . . .. 38

X Contents

3.3.3 Standby Parallel Mode with Compensators for Additional and Counter Voltage . . . . . . . . . . 39

3.4 Changeover Mode. . . . . . . . . . . . . . . . . 40 3.4.1 Changeover Mode with Battery Tap. . . . . . 41 3.4.2 Changeover Mode with Thyristor Contactor . 44 3.5 Combined Standby Parallel and Changeover

Mode with Compensator for Additional Voltage. 45 3.6 Assignment of Operating Modes to Communications

Systems. . . . . . . . . . . . . . . . . . . 46 3.7 Further Modes. . . . . . . . . . . . . . . . . . . . . . . . 49 3.7.1 Changeover Mode with Voltage Gates. . . . . . . . . . 49 3.7.2 Parallel Mode with 'Floating' Charge Method. . . . . 50 3.7.3 Parallel Mode with Reduced Number of Battery Cells

and Compensator . . . . . . . . 51 3.7.4 Parallel Mode with End Cells. . . . . . . . . . . . . 51

4 Operating Modes of an Alternating Current Power Supply System . . . . . . 53

4.1 Mains Mode . . . . . . . . . . . . . . . . . . . . . . . 53 4.2 A.C. Changeover Mode. . . . . . . . . . . . . . . . . 53 4.2.1 A.C. Changeover Mode with Interruption ( > 1 s) . . . . . . .. 53 4.2.2 Standby Power Supply Systems. . . . . . . . . . . . . . . . . .. 53 4.2.3 A.C. Changeover Mode with Interruption ( < 1 s) . . . . . . .. 57 4.3 Uninterruptible a.c. Changeover Mode. . . . . . . 59 4.3.1 Immediate Standby System . . . . . . . . . . . . . 60 4.3.2 Un interruptible Standby Power Supply System with

Rotating Converter . . . . . . . . . . . . . . . . . . . . 61 4.3.3 Static Standby Power Supply Systems with Inverters Connected

to Fail-safe d.c. Power Supplies and with Revert-to-mains Unit 62 4.3.4 Static Standby Power Supply Systems with Inverters Connected

to Fail-safe d.c. Power Supplies and without Revert-to-mains Unit. . . . . . . . . . . . . . . . . . . . . 63

4.3.5 Static Uninterruptible Standby Power Supply Systems. 64

5 Public Mains . . . . . . . . . . 69 5.1 Type of Voltage . . . . . . . . 69 5.2 Tolerances of the a.c. Supply Voltage and Supply Frequency 69 5.3 Wave Shape and Distortion Factor of the a.c.

Supply Voltage. . . . . . . . . . . . . . . . . . . . . . . . . . . . 70 5.3.1 Measures for Reducing Retroactive Effects on the Mains Supply 74 5.4 Power Failures. 77

6 Energy Storage. 78

6.1 Stationary Lead-Acid Batteries 78 6.1.1 Requirements........... 78

6.1.2 6.1.3 6.1.4 6.1.5 6.1.6 6.1.7 6.1.8 6.1.9 6.1.10 6.1.11 6.1.12 6.1.13 6.1.14 6.1.15 6.1.16 6.1.17 6.2 6.2.1 6.3 6.4 6.4.1 6.4.2 6.4.3 6.5 6.5.1 6.5.2 6.5.3 6.5.4 6.5.5 6.5.6 6.6

7

7.1 7.1.1 7.1.2 7.1.3 7.1.4 7.2 7.2.1 7.2.2 7.2.3 7.2.4 7.3 7.3.1 7.3.2

Contents XI

Charging and Discharging . . . . . . . . . . . . . . . . . . . . . . Open-Circuit Voltage ........................ . Rated Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Discharging Voltage. . . . . . . . . . . . . . . . . . . . . . . . . . Self-Discharging . . . . . . . . . . . . . . . . . . . . . . . . . . . . Float (Trickle) Charging and Charging Voltage ........ . Initial Charging Voltage (Commissioning) ............ . Capacity ................................ . Efficiency and Charging Factor .................. . DIN Designation of Battery Type . . . . . . . . . . . . . . . . . Battery Design. . . . . . . . . . . . . . . . . . . . . . . . . . . . . Batteries with Tubular Positives. . . . . . . . . . . . . . . . . . . Batteries with Plante Plates (GroE) ................ . Comparison of Lead-Acid Batteries . . . . . . . . . . . . . . . . Vent Plugs .............................. . Valve-Regulated Lead-Acid Batteries. . . . . . . . . . . . . . . . Stationary Alkaline Batteries. . . . . . . . . . . . . . . . . . . . . Nickel-Cadmium Batteries in Telecommunications ..... . Lithium Primary Batteries ..................... . Design Pointers . . . . . . . . . . . . . . . . . . . . . . . . . . . . Standby Time (Backup Time) ................... . Number of Cells. . . . . . . . . . . . . . . . . . . . . . . . . . . . Capacity ................................ . Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Surveillance of Vented Batteries .................. . Surveillance of Valve-Regulated Lead-Acid Batteries ..... . Battery Monitoring . . . . . . . . . . . . . . . . . . . . . . . . .. A Statement of the Principle of Battery Service ......... . Battery Inspections . . . . . . . . . . . . . . . . . . . . . . . . . . Capacity Checks. . . . . . . . . . . . . . . . . . . . . . . ..... Installation of Batteries. . . . . . . . . . . . . . . . . . . . . . . .

Basic Circuits and Process Control . . . . . . . . . . . . . . . . .

Rectifier Circuits ........................... . Half-wave Rectifier . . . . . . . . . . . . . . . . . . . . . .... . Centre-tap Circuit .......................... . Bridge Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Three-phase Bridge Circuit. .................... . Stabilizing and Control Procedures. . . . . . . . . . . . . ... . Pulse-Sequence Control. . . . . . . . . . . . . . . . . . . . . . . . Pulse-Width Control . . . . . . . . . . . . . . . . . . . . . . . . . Phase Angle Control . . . . . . . . . . . . . . . . . . . . . . . . . Distribution and Design of Trigger Pulses ............ . Rectifying with Stabilization. . . . . . . . . . . . . . . . . . . . . Semi-controlled Single-Phase Bridge Circuit .......... . Fully-controlled Three-Phase Bridge Circuit . . . . . . . . . . .

78 80 81 81 83 83 85 86 86 88 88 89 93 94 94 95

101 103 104 105 105 105 105 111 113 115 116 118 119 123 127

129

129 129 129 129 130 131 131 131 132 134 136 136 136

XII Contents

7.4 D.C.jD.C. Conversion with Stabilization. . . . . . . . . . . . .. 140 7.4.1 D.C. Controller Circuit. . . . . . . . . . . . . . . . . . . . . . .. 140 7.5 Inverting with Stabilization . . . . . . . . . . . . . . . . . . . .. 141 7.5.1 Centre-tap Circuit. . . . . . . . . . . . . . . . . . . . . . . . . .. 142

8 Applications of Control Systems in Power Supply Devices. . .. 144

8.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 144 8.2 The Operation of Open- and Closed-loop Control

Systems. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 144 8.3 Components of the Closed-loop Control System. . . . . . . .. 146 8.3.1 Final Control Element . . . . . . . . . . . . . . . . . . . . . . .. 146 8.3.2 Controlled Object. . . . . . . . . . . . . . . . . . . . . . . . . .. 147 8.3.3 Control Equipment . . . . . . . . . . . . . . . . . . . . . . . . .. 147 8.4 Operational Amplifiers in the Regulator. . . . . . . . . . . . .. 148 8.4.1 Error and Deviation. . . . . . . . . . . . . . . . . . . . . . . . .. 150 8.4.2 Classification of Regulators . . . . . . . . . . . . . . . . . . . .. 151 8.5 Controlled Rectifiers with Thyristor Power Section . . . . . .. 155 8.5.1 Power Section . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 155 8.5.2 Control Section . . . . . . . . . . . . . . . . . . . . . . . . . . .. 155 8.5.3 Behaviour of the Output Voltage and Dynamic Response ... 160 8.5.4 Type Designation . . . . . . . . . . . . . . . . . . . . . . . . . .. 161 8.6 Controlled Power Supply Equipment with Transistor

Power Section. . . . . . . . . . . . . . . . . . . . . . . . . . . .. 162 8.6.1 Rectifiers with Linear Regulators. . . . . . . . . . . . . . . . .. 163 8.6.2 Rectifiers with Switching Regulators. . . . . . . . . . . . . . .. 163 8.6.3 Switching-mode Power Supplies. . . . . . . . . . . . . . . . . .. 165 8.6.4 D.C.jD.C. Converters. . . . . . . . . . . . . . . . . . . . . . . .. 165 8.6.5 Pulse Inverters. . . . . . . . . . . . . . . . . . . . . . . . . . . .. 172

9 Switching Mode Power Supplies . . . . . . . . . . . . . . . . . .. 176

9.1 Type 48 V/12 A (60 VI10 A) . . . . . . . . . . . . . . . . . . . .. 176 9.1.1 General and Application. . . . . . . . . . . . . . . . . . . . . .. 176 9.1.2 Modes of Operation. . . . . . . . . . . . . . . . . . . . . . . . .. 177 9.1.3 Survey Diagram of the Power Supply System. . . . . . . . . .. 177 9.1.4 Survey Diagram and Functioning Principle of the Rectifier

Module 48 V/12A (60 V/lO A). . . . . . . . . . . . . . . . . . .. 178 9.1.5 Technical Data. . . . . . . . . . . . . . . . . . . . . . . . . . . .. 180 9.2 Type 48 V (60 V)/30 A and 100 A. . . . . . . . . . . . . . . . .. 181 9.2.1 General and Application. . . . . . . . . . . . . . . . . . . . . .. 181 9.2.2 Modes of Operation. . . . . . . . . . . . . . . . . . . . . . . . .. 182 9.2.3 Survey Diagram of the Power Supply System. . . . . . . . . .. 182 9.2.4 Survey Diagram, Block Diagram and Functioning Principle

of the Rectifier Module 48 V (60 V)/30 A and 100 A . . . . . .. 186 9.2.5 Technical Data. . . . . . . . . . . . . . . . . . . . . . . . . . . .. 196

9.3 9.3.1 9.3.2 9.3.3 9.3.4

9.3.5 9.4 9.4.1 9.4.2 9.4.3 9.4.4

9.4.5 9.5

10

10.1 10.1.1 10.1.2 10.1.3 10.1.4

10.2 10.2.1 10.2.2 10.2.3 10.2.4

10.3 10.3.1 10.3.2 10.3.3 10.3.4 10.3.5 10.4

11 11.1 11.1.1 11.1.2 11.1.3 11.1.4

11.1.5

Contents XIII

Type 48 V /120 A (60 V /100 A) ................... . General and Application . . . . . . . . . . . . . . . . . . . . . . . Modes of Operation ......................... . Survey Diagrams of the Power Supply System 400 . . . . . . . Survey Diagram, Block Diagram and Functioning Principle of the Rectifier Module 48 V/120 A (60 V/1OO A) ........ . Technical Data. . . . . . . . . . . . . . . . . . . . . . . . . . . .. Type 48 V (60 V, 67 V)/50 A and 100 A ............. . General and Application . . . . . . . . . . . . . . . . . . . . . . . Modes of Operation ......................... . Survey Diagram of the Power Supply System. . . . . . . . . . . Survey Diagram and Functioning Principle of the Rectifier Module 48 V (60 V, 67 V)/50 A and 100 A. . ..... Technical Data. . . . . . . . . . . . . . . . . . . . . . . . . . . . . Power Supply Controller. . . . . . . . . . . . . . . . . . .....

Thyristor Controlled Rectifiers. . . . . . . . . . . . . . . . . . . .

Type 48 V (60 V)/2OO A. . . . . . . . . . . . . . . . . . . . . . . . General and Application . . . . . . . . . . . . . . . . . . . . . . . Modes of Operation ......................... . Survey Diagrams of the Power Supply System . . . . . . . . .. Survey Diagram and Functioning Principle of the Rectifier Unit 48 V (60 V)/2OO A .................. . Type 48 V (60 V)/lOO0 A ...................... . General and Application . . . . . . . . . . . . . . . . . . . . . . . Modes of Operation ......................... . Survey Diagram of the Power Supply System. . . . . . . . . . . Survey Diagram and Functioning Principle of the Rectifier Unit 48 V (60 V)/l000 A ...................... . Assemblies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Regulation Module A3 . . . . . . . . . . . . . . . . . . . . . . . . Control Module A9. . . . . . . . . . . . . . . . . . . . . . . . . . Trigger-Pulse Transformer Module All (A21) ......... . Battery- and Thermo Disconnection Module A16 ....... . 12-Pulse-Regulation Module A23 ................. . Technical Data. . . . . . . . . . . . . . . . . . . . . . . . . . . ..

Magnetically Controlled Rectifiers ................. .

Types 24 V to 220 V /10 A to 400 A ................ . General and Application . . . . . . . . . . . . . . . . . . . . . . . Modes of Operation ......................... . Survey Diagram of the Power Supply System. . . . . . . ... . Survey Diagram and Functioning Principle of the Rectifier Unit 24 V to 220 V/10 A to 400 A ................. . Technical Data. . . . . . . . . . . . . . . . . . . . . . . . . . . . .

196 196 196 196

206 213 213 213 215 215

215 217 220

226

226 226 226 226

228 232 232 233 233

233 235 235 235 245 245 246 249

250

250 250 251 251

252 254

XIV Contents

12 D.C./D.C. Converter. . . . . . . . . . . . . . . . . . . . . . . . .. 255

12.1 Type 50 W to 200 W . . . . . . . . . . . . . . . . . . . . . . . .. 255 12.1.1 Application............................... 256 12.1.2 Modes of Operation. . . . . . . . . . . . . . .. . . . . . . . . .. 256 12.1.3 Survey Diagram and Functioning Principle. . . . . . . . . . .. 256 12.1.4 Technical Data. . . . . . . . . . . . . . . . . . . . . . . . . . . .. 260 12.2 Type 750 W. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 260 12.2.1 Application............................... 261 12.2.2 Modes of Operation. . . . . . . . . . . . . . . . . . . . . . . . .. 261 12.2.3 Survey Diagram and Functioning Principle. . . . . . . . . . .. 261 12.2.4 Technical Data. . . . . . . . . . . . . . . . . . . . . . . . . . . .. 263

13 D.C.I A.C. Inverters . . . . . . . . . . . . . . . . . . . . . . . . .. 265

13.1 Type 2.5 kVA. . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 265 13.1.1 Application............................... 265 13.1.2 Type Designation . . . . . . . . . . . . . . . . . . . . . . . . . .. 265 13.1.3 Modes of Operation. . . . . . . . . . . . . . . . . . . . . . . . .. 266 13.1.4 Survey Diagram of the Power Supply System. . . . . . . . . .. 266 13.1.5 Survey Diagram, Block Diagram and Functioning Principle of

the d.c./a.c. Inverter Module 2.5 kVA. . . . . . . . . . . . . . .. 266 13.1.6 Technical Data. . . . . . . . . . . . . . . . . . . . . . . . . . . .. 272 13.2 Type 15 kV A (3 x 5 kV A). . . . . . . . . . . . . . . . . . . . . .. 272 13.2.1 General and Application . . . . . . . . . . . . . . . . . . . . . .. 272 13.2.2 Type Designation . . . . . . . . . . . . . . . . . . . . . . . . . .. 273 13.2.3 Modes of Operation. . . . . . . . . . . . . . . . . . . . . . . . .. 273 13.2.4 Survey Diagram of the Power Supply System. . . . . . . . . .. 273 13.2.5 Survey Diagram and Functioning Principle of the d.c./a.c.

Inverter 15 kVA (3 x 5 kVA) . . . . . . . . . . . . . . . . . . . .. 273 13.2.6 Technical Data. . . . . . . . . . . . . . . . . . . . . . . . . . . .. 279

14 Static UPS Systems. . . . . . . . . . . . . . . . . . . . . . . . .. 280

14.1 Type 10 to 500 kVA. . . . . . . . . . . . . . . . . . . . . . . . .. 280 14.1.1 Application............................... 280 14.1.2 Modes of Operation. . . . . . . . . . . . . . . . . . . . . . . . .. 280 14.1.3 Overview................................ 281 14.1.4 Survey Diagram and Functioning Principle. . . . . . . . . . .. 284 14.1.5 Technical Data. . . . . . . . . . . . . . . . . . . . . . . . . . . .. 297

15 Diesel Generating Sets . . . . . . . . . . . . . . . . . . . . . . .. 299

15.1 Standby Power Supply System with Fully Automatic Mains Failure Control . . . . . . . . . . . . . . . .. 299

15.1.1 Motor and Generator. . . . . . . . . . . . . . . . . . . . . . . .. 299 15.1.2 Switchgear Control Cubicle . . . . . . . . . . . . . . . . . . . .. 300

15.2

15.2.1 15.3 15.4 15.5

16

16.1 16.2

16.3 16.3.1 16.3.2 16.3.3

17

17.1 17.2 17.3 17.4

17.4.1 17.4.2 17.4.3 17.5 17.5.1 17.5.2 17.5.3 17.5.4 17.6 17.6.1 17.6.2 17.6.3 17.6.4

17.6.5

18 18.1 18.1.1 18.1.2 18.1.3

Contents XV

Mains Independent Island Power Supply System with Fully Automatic Alternating Operation . . . . . . Switchgear Control Cubicle . . . . . . . . . . . . . . . . . . . . . Fully Automatic Electronic Control System. . . . . . . . . ... Fuel Distribution System. . . . . . . . . . . . . . . . . . . . . . . Lubrication Oil Distribution System. . . . . . . . . . . . . ...

Special Features for Transmission System Power Supplies ... .

Power Supply for Radio Link Apparatus . . . . . . . . .... . Power Supply for Ground Communication Stations for Telecommunications Satellites. . . . . . . . . . . . . . ... . Mains-Independent Power Supply Systems ........... . Primary Power Sources ....................... . Solar Power Supply Systems .................... . Passive Cooling System ....................... .

Grounding and Potential Equalization ....

304 304 309 315 315

316

316

318 322 322 329 334

337

Protective Grounding. . . . . . . . . . . . . . . . . . . . . . . .. 337 Functional Grounding . . . . . . . . . . . . . . . . . . . . . . .. 339 Functional and Protective Grounding. . . . . . . . . . . . . .. 341 Selection and Design of Grounds and Grounding Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 343 Types of Grounds . . . . . . . . . . . . . . . . . . . . . . . . . .. 344 Grounding Main Conductor. . . . . . . . . . . . . . . . . . . .. 345 Grounding and Potential-Equalization Conductors . . . . . .. 345 Design Pointers for Grounding Systems. . . . . . . . . . . . .. 349 Specific Ground Resistance. . . . . . . . . . . . . . . . . . . . .. 349 Measurement of Specific Ground Resistance . . . . . . . . . .. 349 Measurement of Grounding Resistance . . . . . . . . . . . . .. 350 Calculation of Ground Resistance. . . . . . . . . . . . . . . . .. 352 Protection against Overvoltage and Interference. . . . . . . .. 353 Overvoltage Sources. . . . . . . . . . . . . . . . . . . . . . . . .. 354 Interference in Telecommunications Systems . . . . . . . . . .. 355 Design of the Distribution Network for EWSD Systems . . .. 357 Design of Grounding, Potential Equalization and Lightning Protection for EWSD Systems. . . . . . . . . . . . . . . . . . .. 361 Special Requirements for Lightning Protection in Telecommuni-cations Towers. . . . . . . . . . . . . . . . . . . . . . . . . . . .. 365

Protective Measures. . . . . . . . . . . . . . . . . . . . . . . . .. 368 Protection by Disconnection or Indication . . . . . . . . . . .. 372 Protective Measures in the TN Supply System. . . . . . . . .. 374 Protective Measures in the TT Supply System . . . . . . . . .. 377 Protective Measures in the IT Supply System. . . . . . . . . .. 378

XVI Contents

18.1.4 18.2 18.2.1 18.2.2 18.2.3 18.2.4

Fault Current-Operated Protective Circuit ........... . Protection without Disconnection or Indication . . . . . . . . . Protective Insulation . . . . . . . . . . . . . . . . . . . . . . . . . Equipment with Protectively Insulated Parts . . . . . . . . . .. Protective Low Voltage and Functional Low Voltage. Protective Separation. . . . . . . . . . . . . . . . . . . . . . . . .

379 381 381 382 383 384

Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 385

Index. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 387