1、I 4862591 0679393 523 m I NTE R NAT I O N AL TE LEC OM M U N I CAT I O N U N I O N DIRECTIVES concerning the protection of telecommunication lines against harmful effects from electric power and electrified railway lines Volume II Calculating induced voltages and currents in practical cases ITU-T TE
2、 LEC OMM U NI CATI ON STAN DARD I ZAT I O N SECTOR OF ITU 1999 ia 48b25L Ob79394 4bT 81 INTERNATIONAL TELECOMMUNICATION UNION DIRECTIVES concerning the protection of telecommunication lines against harmful effects from electric power and electrified railway lines Volume II Calculating induced voltag
3、es and currents in practical cases ITU-T TE LEC OMM UN I CAT I ON STANDARD I ZATION SECTOR OF ITU 1999 E 48b25ell Ob79395 3Tb o m 1999 All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and micr
4、ofilm, without permission in writing from the ITU. 48b259L Ob79396 232 PREFACE (to the 1989 edition) The rapid development of new technologies in telecommunications, electric power transmission and distribution, and electric railway systems has made the earlier issue of the Directives (1960 edition)
5、 out-of-date and this former issue is therefore being replaced completely. The present Directives (1988 edition) have been established by the International Telegraph and Telephone Consultative Committee (CC) to give clear advice on how adverse electromagnetic effects on telecommunications lines from
6、 nearby electric power or electric railway installations may be minimized. The Directives have been based on the latest information that is available. The new Directives have been prepared in close cooperation with the following international organizations: - - Representatives from these organizatio
7、ns have participated in preparation of the text of the Directives. The two organizations support the underlying principles from which these texts have been derived, and the guidelines in the Directives which have been given. Such guidelines normally related to general cases which are described. It i
8、s left to national organizations to establish more detailed regulations which apply to particular cases. The new Directives are divided into a series of separate volumes, each dealing with a particular part of the complete subject. Each volume can be used independently. Modern calculation methods wh
9、ich are suitable for computer techniques have been incorporated. Numerical values are used to define desirable limits which should be followed when the recommended technical measures are taken. In general, it should not be necessary to exceed these limits, although some special cases may arise where
10、 it is either uneconomical or impractical to do so (e.g. in narrow valleys). In such cases, mutual agreement based on the principles set out in the Directives should be reached. Guidance on administration, economic and particularly legislation matters have been omitted deliberately since they are co
11、nsidered to be outside the technical scope of the advice given in the new Directives. In consequence, the rules of procedure which should be followed by telecommunications operators, and electric power and electric railway authorities have not been covered. Nevertheless, the three international orga
12、nizations which have worked together to produce the new Directives, “Telecommunications, electric power and electric railway authorities should work together closely and follow the new Directives when seeking solutions to mutual problems. The solutions chosen should be those most acceptable and econ
13、omical overall, and should not confer undue advantages to any participant. We, the undersigned, representing the three organizations, CCITT, UIC and CIGRE, support the work done jointly on behalf of our organizations in producing these Directives. We recommend these Directives to members of CCITT, U
14、IC and CIGRE who seek solutions to mutual disturbance problems.” the Intemational Union of Railways (UIC) the International Conference on Large High Voltage Electric Systems (CIGRE). CCITT, UIC and CIGRE, recommend that: Th. IRMER Director of the CCITT J. BOULEY Secretary-General of UIC G. LEROY Sec
15、retary-General of CIGRE . W 4862591 0679397 179 W TABLE OF CONTENTS Page CHAPTER 1 . INTRODUCTION . 1.1 1.2 1.2.1 1.2.2 1.2.2.1 Aim and scope of the Directives . Structure of the Directives Content of individual volumes Use of the Directives . When studying coupling processes in general 1.2.2.2 When
16、 establishing standards or similar regulations 1.2.2.3 When dealing with danger and disturbance problems in practice . Principle of calculating each type of coupling Classification of calculaiion methods Guide line for choosing the appropriate method . 1.3 1.3.1 1.3.2 1.3.3 Introduction to Volume II
17、 . CHAPTER 2 . GUIDE LINE FOR PRACTICAL CASES . 2.1 General applications scheme . 2.2 General conventions 2.2.1 Zone of influence 2.2.1.1 Inductive coupling . 2.2.1.2 Capacitive coupling . 2.2.1.3 Conductive coupling . 2.2.2 Exposure length 1 2.2.3 Oblique exposure 2.2.4 Crossing 2.3 Parameters used
18、 for basic estimation 2.3.1 Inducing current I 2.3.1.1 Earth fault current of a high voltage line 2.3.1.2 Earth fault current at power stations or sub-stations . 2.3.1.3 Operational current in an ac traction line 2.3.1.4 Short-circuit current is a traction line 2.3.2 Coupling impedance Z 2.3.3 Scree
19、ning factor k . 2.3.4 2.4 2.5 Earthing resistance of a power station or sub-station Calculation of induced voltages and currents in practical cases . Permissible voltages and currents . 1 1 2 2 3 3 3 3 5 5 5 11 13 13 14 14 14 14 14 14 14 15 15 15 15 15 15 15 16 16 16 17 17 V Volume II . Table of Con
20、tents Previous page is blank . I 4662592 Ob79398 005 W Page 17 37 37 37 2.6 Protection measures 2.7 Numerical example using basic estimation . 2.7.1 2.7.2 Open wire telecommunication line induced by a high-reliability power line . Telecommunication cable induced by an electrified railway line . CHAP
21、TER 3 - CALCULATION OF CAPACITIVE COUPLING . 3.1 General 3.1 . 1 Preliminary remarks, assumptions 3.1.2 Most common symbols used . 3.2 Method using the coupling coefficients 3.2.1 General considerations 3.2.2 3.2.2.1 Coupling cases 3.2.2.2 Capacitance to earth for telecom circuit, Co . 3.2.2.3 Numer
22、ical coefficient for electric lines go 3.2.2.4 Functions n and N for different line conditions 3.2.2.5 Shielding factors, qo . qp, qt . 3.2.3 Simplified calculation using graphs 3.2.3.1 General 3.2.3.2 Curves for functions n(a), N(a) and their derivatives Calculation of coupling functions for lines
23、of usual constructions . 45 45 45 47 48 48 55 55 57 58 58 59 63 63 63 3.2.3.3 Application 64 3.2.4 Calculation for a few special cases . 70 3.2.4.1 Method of equivalent radius and geometric mean distance 70 3.2.4.2 Formulae for calculating the coupling 74 3.2.4.3 Numerical values for coupling quanti
24、ties 77 Annex A (to Section 3.2) - Shielding effects of earth wires associated with either the inducing or the A.l Development of the formulae . 83 A.2 Numerical example 87 3.3 Method using matrix operations 92 3.3.1 Basic mairix formulae . 92 3.3.1.1 Presentation of the systems and basic formulae 9
25、2 3.3.1.2 Lines without shielding conductors 94 3.3.1.3 Lines with shielding conductors 95 3.3.1.4 Formula for total length 98 3.3.2 Application to the various types of telecommunication lines . 99 3.3.2.1 Basis of line classification . 99 telecommunication lines 83 vi Volume II . Table of Contents
26、4862591 Obici399 T41 Page 3.3.3 Conductor-to-earth (common mode) voltages and currents 3.3.3. i Isolated telecommunication lines 3.3.3.2 Earthed telecommunication lines 3.3.4 Differential mode voltages and currents . 3.3.4.1 Preliminary note 3.3.4.2 Case of isolated conductor pairs . 3.3.4.3 Case of
27、 earthed conductor pairs 3.3.5 Mixed telecorn lines 3.3.6 Procedure for calculating by matrix method . Annex A (to Section 3.3) - Illustration of matrix applications in calculating the effects of capacitance coupling . Arrangements and conditioning of power and telecom lines to be studied . Potentia
28、l coefficient and coupling factor matrices A.l A.2 A.3 A.3.1 A.3.2 A.3.3 Results for mixed and pair systems . A.3.3.1 System composed of individual conductors A.3.3.2 System composed of pair circuits . A.3.4 Results for different separation distances Voltages and currents caused by capacitive coupli
29、ng . Voltages of isolated telecom conductors . Discharge currents of earthed telecom conductors . CHAPTER 4 - CALCULATION OF INDUCTIVE COUPLING 4.1 Self and mutual impedance of conductors with earth return . 4.1.1 General remarks 4.1.2 Basic and specific cases 4.1.3 List of symbols and the units use
30、d 4.1.3.1 List of symbols 4.1.3.2 Units used 4.1.4 Basic expressions of self and mutual impedance 4.1.5 Expressions for small values of x 4.1.5.1 External and mutual impedance (Carson-Clem formulas) 4.1 S.2 Internal impedance (geometric mean radius) 4.1.5.3 Group of conductors . 4.1.6 Expressions in
31、 polynomial form . 4.1.7 Complex image formulas 4.1.8 Expression in form of series 4.1.9 Guideline to choose an adequate formula . 4.1.10 Table and curves of inductive coupling Volume II - Table of Contents 100 100 104 111 111 112 117 120 121 123 123 125 129 129 129 132 132 132 133 141 141 141 141 1
32、42 142 - 147 147 149 149 154 156 159 160 162 164 165 vii = 4862571 0b400 593 I 4.1.1 1 Specific cases 4.1.1 1.1 Lines of finite length . 4.1.1 1.2 Equivalent resistivity for a horizontally stratified earth . 4.1.12 References (to Section 4.1) . 4.2 Mutual impedance between a metallic loop and a wire
33、-to-earth circuit . 4.2.1 4.2.1.1 General considerations 4.2.1.3 Simplified formulas of the earth correction terms 4.2.1.4 Series expansions of earth correction terms 4.2.1.5 Numerical values for demonstration . 4.2.2 Metallic loop composed of threc-phase line with balanced currents 4.2.2.1 General
34、considerations 4.2.2.2 Balanced three-phase system 4.2.2.3 Balanced components of unsymmctrical three-phase system . 4.2.2.4 Numerical example . Annex A (to Section 4.2) - Evaluation of the mutual impedance between a balanced three-phase line without earth return current and a wire-to-earth circuit
35、4.3 Screening effects of earthed conductors . 4.3.1 General comments . 4.3.2 4.3.2.1 Assumptions concerning perfect earthing . 4.3.2.2 Single screening conductor . 4.3.2.3 Case of two screening conduciors (resultant screening factor) . Expressions for oblique exposures and crossings . Metallic loop
36、composed of two conductors such as open wire line Continuously earthed long conductors 4.3.2.4 The case of several inducing and screening conductors . Screening current (factor) with end-effect 4.3.4.2 Calculation procedures Screening effect of a return conductor 4.3.5.1 General description . 4.3.5.
37、2 Description of the most common case 4.3.6 Screening effects of metal sheathed telecommunication cables 4.3.6.1 Particularities of sheath as tubular screening conductor . 4.3.6.2 Procedures for cases with different earthing of the sheath 4.3.6.3 Quantities regarding the screening effect 4.3.6.5 Scr
38、eening factor improvement by earthing conductors in the core . 4.3.6.6 Screening effect of the core-sheath circuit closed through earth capacitance . 4.3.3 4.3.4 4.3.4.1 End-effect phenomena Screening conductor earthcd at the ends . 4.3.5 4.3.6.7 Proximity of several telecommunication cables Page 17
39、0 170 171 176 179 180 180 180 183 184 189 194 194 194 195 196 200 203 203 208 208 208 213 220 223 226 226 234 245 245 248 252 252 259 259 292 293 298 . VI11 Volume LI . Table of Contents 48b2591 0679401 42T E Page 4.3.7 4.3.7.1 Preliminary comments 4.3.7.2 Procedures for the case of single cable wit
40、h different earthing of the sheath . Screening effects of metal sheathed power cables 4.3.7.3 Case of perfectly earthed sheaths 4.3.7.4 Short cable with sheath earthed at ends only 4.3.7.5 Short cable with continuously earthed sheath . Annex A (to Section 4.3) -Evaluation of the screening factor for
41、 different separations . Annex B (to Section 4.3) -Transmission formulas for lines induced by uniform electric field References (to Section 4.3) . CHAPTER 5 - CALCULATION OF CONDUCTIVE COUPLING 5.1 General 5.1 .I Conductive coupling - Ground potential rise (GPR) 5.1.2 Assumpiions concerning electric
42、al properties of soil . 5.1.3 Most common symbols used . 5.2 Ground potential rise (GPR) evaluation 5.2.1 Electrode GPR . 5.2.1 . 1 Basic expression 5.2.1.2 GPR of power-line tower footings 5.2.1.3 GPR of station ground grids 5.2.2 Area of GPR 5.2.2.1 Potential given by the equivalent hemisphere . 5
43、.2.2.2 Potential in the case of stratified soil 5.2.2.3 Total ground potential produced by more than one electrode . Lines passing through the zone of GPR Cable with insulating covering 5.3 5.4 5.4.1 5.4.2 Potential transferred to earth electrode or short buried cable 5.4.3 Potential transferred to
44、long buried cable . 5.4.3.1 General considerations Areas in which dangerous phenomena appear 5.4.3.2 Calculation by sectionaiization technique . Calculation for long cable by integration technique . 5.4.3.4 Calculation by transmission line modelling Lines entering the station GPR . 5.4.3.3 5.5 5.5.1
45、 Statement of the problem 5.5.2 Plastic-covered cable . 5.5.3 Metallic sheathed cable in contact with the earth 5.5.3.1 Calculation by sectionalization technique 5.5.3.2 Calculation by transmission line modelling 303 303 305 306 313 314 316 321 326 327 327 327 328 329 330 330 330 330 332 335 335 341
46、 342 342 345 345 345 348 348 351 360 366 369 369 369 371 371 374 Volume II . Table of Contents ix 4862593 Ob79402 366 Page 5.6 Distributed parameters of the sheath-to-earth circuit 375 References 377 Annex A (to Chapter 5) - Basis of calculating the conductive coupling by the sectionalization techni
47、que Annex E3 (to Chapter 5) - Numerical example for demonstrating the calculation by sectionalization Annex C (to Chapter 5) -Basis of calculating the conductive coupling by the integration technique 3 378 technique 383 386 CHAPTER 6 . INDUCING CURRENTS AND VOLTAGES 387 Currents and voltages in case
48、 of a.c. power systems 387 6.1.1 General 387 6.1.2 Currents in normal operation 387 Currents in directly earthed network in faulty conditions . 6.1.4.2 Compensating effects of power lines Currents causing potential rise Currents in network with neutral isolated or earthed through arc suppression coi
49、l 6.1.7 Harmonics . 395 Inducing currents and voltages in the case of a.c. electrified railway systems . 6.1 6.1.3 Currents in short-circuit conditions . 387 6.1.4 387 6.1.4.1 Inducing currents . 387 390 6.1.4.3 392 6.1.5 395 6.1.6 Voltages in power systems 395 6.2 397 6.2.1 Introduction . 6.2.2 Characteristics of a.c. traction systems . 6.2.2.1 6.2.2.2 Types of traction feeding systems . 6.2.3 Principle for calculations . 6.2.3.1 Cases to be calculated . 6.2.3.2 Procedures for calculations . 6.2.4 Supply arrangements for a.c. electric traction systems . Calculation of inducing curr
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