1、INTERNATIONAL TELECOMMUNICATION UNION CCITT THE INTERNATIONAL TELEGRAPH AND TELEPHONE CONSULTATIVE COMMITTEE DIRECTIVES concerning the protection of telecommunication lines against harmful effects from electric power and electrified railway lines VOLUME VI1 PROTECTIVE MEASURES AND SAFETY PRECAUTIONS
2、 Geneva 1989 INTERNATIONAL TELECOMMUNICATION UNION CCITT THE INTERNATIONAL TELEGRAPH AND TELEPHONE CON SULTATIVE COMMITTEE DIRECTIVES concerning the protection of telecommunication lines against harmful effects from electric power and electrified railway lines VOLUME VI1 PROTECTIVE MEASURES AND SAFE
3、TY PRECAUTIONS Geneva 1989 ISBN 92-61 -04091 -8 I.T.U. PREFACE The rapid development of new technologies in telecommunications, electric power transmission and distrib- ution, and electric railway systems has made the earlier issue of the Directives (1960 edition) out-of-date and this former issue i
4、s therefore being replaced completely. The present Directives (1988 edition) have been established by the International Telegraph and Telephone Consultative Committee (CCITT) to give clear advice on how adverse electromagnetic effects on telecommunications lines from nearby electric power or electri
5、c 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 : - the International Union of Railways (UIC) - the International Conference
6、 on Large High Voltage Electric Systems (CIGRE). Representatives from these organizations 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
7、been given. Such guidelines normally relate to general cases which are described. It is 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
8、complete subject. Each volume can be used independently. Modern calculation methods which are suitable for compu- ter 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 sho
9、uld not be necessary to exceed these limits, although some special cases may anse where it is either uneconomical or impractical to do so (e.g. in narrow valleys). In such cases, mutual agree- ment based on the principles set out in the Directives should be reached. Guidance on administration, econo
10、mic and particularly legislation matters have been omitted deliberately since they are considered 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 elect
11、ric rail- way authorities have not been covered. Nevertheless, the three international organizations which have worked together to produce the new Direc- tives, CCIT, UIC and CIGRE, recommend that : “Telecommunications, electric power and electric railway authorities should work together closely and
12、 fol- low the new Directives when seeking solutions to mutual problems. The solutions chosen should be those most accept- able and economical overall, and should not confer undue advantages to any participant. We, the undersigned, representing the three organizations, CCITT, UIC and CIGRE, support t
13、he work done jointly on behalf of our organizations in producing these Directives. We recommend these Directives to members of CCITT, UIC and CIGRE who seek solutions to mutual disturbance problems.” Th. IRMER Director of the CCLT J. BOULEY Secretary-General of UIC G. LEROY Secretary-General of CIGR
14、E TABLE OF CONTENTS Page CHAPTER 1 . INTRODUCTION . 1.1 1.2 Aim and scope of the Directives Structure of the Directives . 1.2.1 Content of individual volumes . 1.2.2 Use of the Directives 1.2.2.1 When studying coupling processes in general . 1.2.2.2 When establishing standards or similar regulations
15、 . 1.2.2.3 When dealing with danger and disturbance problems in practice . CHAPTER 2 . ASSIGNMENT OF PROTECTIVE MEASURES TO DIFFERENT CASESOF DANGER AND DISTURBANCE CHAPTER 3 . PROTECTIVE MEASURES APPLIED ON THE TELECOMMUNICATION SIDE . 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 Increasing the distance bet
16、ween telecommunication line and power line . Replacement of overhead lines by cables 3.2.1 Replacernent of unscreened overhead cables and open wire lines by screened cables . 3.2.2 Use of buried cables to avoid direct contact or arc-overs Cable with improved screening factor . Cables with increased
17、dielectric strength . 3.4.1 Wire-metallic sheath (wire-earth in the case of an all-plastic sheath) . 3.4.2 Wire-wire . 3.4.3 Sheath-earth . Optical fibre cables . Radio-relay links . Multiplex systems . 3.7.1 Carrier-frequency systems 3.7.2 PCM-systems . Screening conductors Line transformers 3.9.1
18、Terminations at the ends of the line 3.9.2 Sectionalization by transformers Previous page is blank . Volume W . TaMe of Contents 1 1 2 2 3 3 3 3 5 7 7 7 7 8 8 10 10 11 11 11 12 12 12 12 12 13 13 14 v 3.10 3.11 3.12 3.13 3.14 3.15 3.16 3.17 3.18 3.19 3.20 Isolating transfomers Neutralizing transforme
19、rs Active reduction system Protective coils Coupling coils . Drainage coils . Improvement of balance 3.16.1 Prevention of earth return . 3.16.2 Improvement of line balance 3.16.3 Improvement of balance of the equipment connected . Overvoltage arresters 3.17.1 Air gap protectors with metallic electro
20、des 3.17.2 Carbon block arresters 3.17.3 Gas discharge tubes (GDTs) . 3.17.4 Earthing relays . 3.17.5 Acoustic shock suppressors Voltage-limiting semi-conductor components . Protection from contact with high voltages 3.19.1 Distances and insulation . 3.19.2 Series devices for overcurrent protection
21、Particularities of the interconnection between telecommunication circuits of power distributors with telecommunication lines of the public network Page 14 14 16 17 18 19 19 20 20 21 22 23 23 24 26 27 28 29 29 30 31 CHAPTER 4 . PROTECTION OF STAFF AND OF TELECOMMUNICATION INSTALLATIONS AGAINST THE AD
22、VERSE EFFECTS OF HIGH EARTH POTENTIALS IN THE NEIGHBOURHOOD OF ELECTRIC INSTALLATIONS . 33 4.1 Gencrai . Limiting values 33 4.2 Rise in earth potential . 33 33 33 33 4.2.1 4.2.2 4.2.3 Networks of which the neutral point is earthed directly or through a low impedance . Networks of which the neutral p
23、oint is earthed through an arc suppression coil Networks of which the neutral point is isolated 4.3 Various types of earth faults 34 4.3.2 Faults outside the generating station or sub-station . 34 4.3.1 Faults within the generating station or sub-station 34 4.3.3 Faults on towers . 34 4.3.4 Faults i
24、n mid-span 34 VI Volume M . Table of Contents = 4b2571 Ob43302 73T II Page 4.4 Methods for the protection of telecommunication installations against adverse effects of rise of earth potential . 4.4.1 Telecommunication cables serving generating stations or sub-stations . 4.4.1.1 Protection against th
25、e adverse effects of current circulation in the cable sheath . 4.4.1.2 Protection against dangerous differences of potential 4.4.1.3 Arrangement at points accessible to the public Telecommunication cables passing the zone of influence of the earthing system of a 4.4.2 generating station or sub-stati
26、on . Telecommunication cables passing near transmission towers . Protective arrangements for overhead telecommunication lines serving generating stations or sub-stations . Examples of protective devices in current use for the protection of telecommunication circuits at sub-station inputs 4.5.1 Gener
27、al principles 650 V for high-reliability lines 4.4.3 4.4.4 4.5 4.5.1.1 Rise in earth potential of sub-station less than 430 V for normal lines or 4.5.1.2 Rise in earth potential of sub-station greater than 430 or 650 V Description of operation of devices 4.5.2.1 Type 1 protection 4.5.2.2 Type 2 prot
28、ection - For a rise in sub-station potential up to approximately 4 kV 4.5.2.3 Type 3 protection 4.5.2.4 Typ 4 - For any earth potential rise 4.5.2.5 Example of another protection system . 4.5.2 CHAPTERS- MEASURES APPLIED ON THE POWER-SIDE TO REDUCE DANGER AND 5.1 5.2 5.3 5.4 5.5 DISTURBANCES . Earth
29、 wires of overhead power lines with an improved screening factor Cables with improved screening factor Compensating conductor in vicinity of a power line Limitation of inducing current in three-phase ac systems 5.4.1 increasing the zero-sequence impedance 5.4.2 Increasing the zero-sequence impedance
30、 and the positive sequence impedance - Separation of systems . Reducing the inductive coupling of ac electrified railway systems 5.5.1 5.5.2 Use of additional return conductors Use of coaxial type feeding cables . Volume VII . Table of Contents 34 34 34 35 36 36 36 37 37 37 37 37 39 39 40 42 44 47 4
31、9 49 50 53 62 62 62 62 63 63 VI1 5.5.3 Use of booster-transformers . 5.5.4 Autotransformers . 5.6 Limitation of harmonics 5.7 Secure installation of power lines 5.7.1 Measures to avoid direct contact 5.7.2 High-reliability power lines 5.8 5.9 Crossing of cable sheaths and transposition of single-cor
32、e power cables . 6.1 General considerations 6.2 Precautions for staff working on lines . Transposing the phase conductors of overhead power lines . 6.2.1 General recommendations 6.2.2 Open-wire lines 6.2.3 Cables 6.2.3.1 Full isolation from earth 6.2.3.2 Insulation from exposed conductors 6.2.3.3 Ge
33、neral earthing . Precautions for staff working in switching centres . 6.3 Page 63 65 68 68 68 68 68 69 71 71 72 72 72 73 73 73 73 VI11 Volume W . Table of Contents = 98b257L Ob83309 702 E CHAPTER1 INTRODUCTION 1.1 Aim and scope of the Directives The present Directives supersede the 1963 edition appr
34、oved by the 2nd Plenary Assembly of CC in New Delhi 1960. The 1963 Directives were amended in 1965, 1974, 1978 and 1982. They provided a comprehensive description of electromagnetic effects due to the close proximity of telecommunication lines to power and electrified railway systems, containing reg
35、ularly updated findings in this field and reflecting the current state of the art. Analyses have shown, however, that in spite of these advantages, the 1963 Directives are not used as widely as expected. The main reasons for this are believed to be that the 1963 Directives form a very bulky book whi
36、ch is hard to handle and in which theoretical considerations tend to prevail over practical advice. Calculation methods and the related models were developed before modem computer technology was available. Since the 1%3 Directives reflected the principal arrangements which appeared in the original f
37、irst issue in 1925, many cross-references became necessary as new clauses were added. In consequence, the VIIth Plenary Assembly of CCT in Geneva 1980 decided to revise the 1963 Directives completely and entrusted Study Group V with the task of producing new Directives for publication in 1988. The n
38、ew Directives are intended to meet a number of requirements, particularly those sought by engineers in the field. Nevertheless, the valuable background advice contained in the 1963 Directives is retained and even ex- panded wherever relevant. As a result, the new Directives should be useful: - to pr
39、actising engineers who seek guidelines on how to deal with danger and disturbance problems; - to scientists and researchers who need a reference book with the most recent findings; - to students who require a textbook with which to become acquainted with electromagnetic coupling phenomena; - to Admi
40、nistrations which need to have a basis to form national regulations and standards. The new Directives have been prepared as a result of close coilaboration between many members of CC. CIGRE and the iC. They therefore describe technical methods for solving mutual problems which are recognized by thes
41、e intemational organizations and which should facilitate coordination between member organizations in user coun- tries. The principal object of the new Directives is to describe ways in which adverse effects from power transmission and distribution lines or from electrified railway lines onto teleco
42、mmunication lines can be reduced or avoided. Such effects may result in danger to personnel, damage to telecommunication equipment, deterioration of telecommunication transmission quality or to disturbance of signailing. Although the advice given in the new Directives has been described for public t
43、elecommunication networks, the basic principles have a more general application, and owners of other networks should decide whether they can be adapted to their own needs. Volume W - Chap. 1 1 13 Structure of the Directives 1.2.1 Content of individual volumes The new Directives are divided into 9 vo
44、lumes, each dealing with a separate part of the overail subjezt matter. The series is made up as follows: Volume I Volume II Volume III Volume IV Volume V Volume VI Volume VII Volume VII Volume IX “Design, construction and operational principles of telecommunication, power and electrified railway fa
45、cilities“ describes these systems and shows why conditions for their mutua coexistence must be established. “Calculating induced voltages and currents in practical cases“ describes the methods for evaluating voltages and currents resulting from capacitive, inductive and conductive coupling in a vari
46、ety of commonly-encountered situations. “Capacitive, inductive and conductive coupling: physical theory and calculation methods“ gives an account of the physical laws governing the relevant phenomena together with mathematical models, and introduces a precise calculation method to evaluate voltages
47、and currents resulting from couplings. “Inducing currents and voltages in elecbified railway systems“ describes traction systems using d.c. and a.c. at various frequencies (16 2/3 Hz, 50 Hz, 60 Hz etc.) in normal operation and under fault conditions. “Inducing currents and voltages in power transmis
48、sion and distribution systems“ describes unbalanced and balanced power systems in normal operation and under fault conditions. “Danger and disturbance“ considen the risk to both equipment and people. “Protective measures and safety precautions“ describes methods which are commonly used to ensure sat
49、isfactory working and operating conditions. “Protective devices“ gives the latest information on devices which may be used to improve safety standads or reduce disturbance of telecommunication systems. Testing methods and measuring apparatus“ describes the methods and apparatus used to determine parameters required for coupling calculations, and to verify the satisfactory operation of protective measures. In addition it deals with testing methods taking into account modem practices in other fields of electromagnetic compatibility (e.g. lightning, high frequency disturbances). Th
