1、 INTERNATIONAL TELECOMMUNICATION UNION ITU-T K.66TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (12/2004) SERIES K: PROTECTION AGAINST INTERFERENCE Protection of customer premises from overvoltages ITU-T Recommendation K.66 ITU-T Rec. K.66 (12/2004) i ITU-T Recommendation K.66 Protection of custome
2、r premises from overvoltages Summary This Recommendation: provides recommendations for bonding and earthing of telecommunication equipment in residential and commercial customer premises; refers to ITU-T Rec. K.21 for equipment resistibility requirements; recommends earthing and bonding requirements
3、 to coordinate with the resistibility requirements of ITU-T Rec. K.21 and the safety requirements of IEC 60950-1; recommends the installation practices for bonding of all services and the installation of SPDs; illustrates problems associated with earthing and bonding and provides solutions for these
4、 earthing and bonding problems. These include: 1) methods to improve the earthing and bonding; 2) methods of providing additional protection external to the equipment; 3) special resistibility and safety requirements; recommends responsibilities for protection at customer premises; refers to draft I
5、EC 62305-3 for protection against direct lightning. Source ITU-T Recommendation K.66 was approved on 14 December 2004 by ITU-T Study Group 5 (2005-2008) under the ITU-T Recommendation A.8 procedure. ii ITU-T Rec. K.66 (12/2004) FOREWORD The International Telecommunication Union (ITU) is the United N
6、ations specialized agency in the field of telecommunications. The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommuni
7、cations on a worldwide basis. The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. The approval of ITU-T Recommendations is covered by the procedu
8、re laid down in WTSA Resolution 1. In some areas of information technology which fall within ITU-Ts purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. NOTE In this Recommendation, the expression “Administration“ is used for conciseness to indicate both a telecom
9、munication administration and a recognized operating agency. Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure e.g. interoperability or applicability) and compliance with the Recommendation is achieved when all of these
10、mandatory provisions are met. The words “shall“ or some other obligatory language such as “must“ and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. INTELLECTUAL PROPERTY RIGHTS ITU dr
11、aws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members
12、or others outside of the Recommendation development process. As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementors are cautioned that this may not re
13、present the latest information and are therefore strongly urged to consult the TSB patent database. ITU 2005 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. ITU-T Rec. K.66 (12/2004) iii CONTENTS Page 1 Scope 1
14、 2 References. 1 3 Definitions 3 4 Abbreviations 3 5 Responsibility . 5 5.1 Building owner . 5 5.2 Manufacturer 5 5.3 Network operator 5 5.4 Customer. 5 6 Risk management . 6 6.1 Sources of damage 6 6.2 Risk assessment 7 6.3 Risk reduction. 8 7 Objectives for bonding configurations and earthing 8 8
15、Protection requirements 8 8.1 Equipotential bonding 8 8.2 a.c. power distribution and SPDs . 12 8.3 Telecommunication lines and SPDs. 12 8.4 Selection of SPDs for installation at point of entry 13 9 Installation of SPDs (primary protectors). 14 9.1 Installation methods for SPDs (primary protection)
16、for different power distribution systems 14 9.2 Examples of installation methods to achieve the requirements of short bond wires 14 9.3 Location of the telecommunication SPD 19 9.4 Safety issues . 19 10 Combination protection units . 20 10.1 Single CPU . 20 10.2 Multiple CPUs 21 11 Implementation. 2
17、1 12 Large installations. 22 Annex A Installation methods for different power systems . 23 A.1 Installation method for TN-S power distribution systems . 23 A.2 Installation method for TN-C-S power distribution systems . 26 A.3 Installation method for TN-C power distribution systems . 31 A.4 Installa
18、tion method for TT power distribution systems . 34 A.5 Installation method for IT power distribution systems. 40 iv ITU-T Rec. K.66 (12/2004) Page Annex B Solutions for earthing and bonding problems 45 B.1 Methods to improve earthing and bonding. 45 B.2 Methods of providing additional protection ext
19、ernal to the equipment . 45 B.3 Special resistibility and safety requirements 45 Appendix I Earthing and bonding scenarios. 45 Appendix II Examples of mitigation measures for different power installations. 49 II.1 TN-C and TN-C-S types. 49 II.2 TT and IT types 49 Appendix III Surge current paths and
20、 resulting potential differences 50 Appendix IV Special resistibility and safety requirements. 52 ITU-T Rec. K.66 (12/2004) v Introduction Overvoltage protection may be required for safety of persons and for protection of equipment. To provide this protection, it is necessary to bond metallic servic
21、es and screens to the building earth and install SPDs at the building entry point on power and telecommunication conductors. This will reduce the risk of people using these services being injured during a.c. fault conditions and during lightning storms. These methods will also provide a level of pro
22、tection for equipment connected to one or more of these services. The building owner may elect to install protection at the building entry point in areas deemed not at risk by the service operator to protect against injury or equipment damage. The increasing use and interconnection of complex electr
23、onic telecommunications equipment, such as ISDN terminals, modems and computers, at customers buildings requires special care for protecting against overvoltages and overcurrents. Such overvoltages and overcurrents include exposure of the serving telecommunications cable and power line to lightning,
24、 and the coupling of a.c. voltages onto the telecommunication cable due to faults on the external power system. Properly configured equipotential bonding within the building helps to achieve the necessary protection, while also helping to ensure the safety of those using terminal equipment. IEC 6095
25、0-1 7 assumes that the telecommunications network operator will install overvoltage protection at the network termination to prevent overvoltages from exceeding 1.5 kV for the majority of surges. The standard way to do this is to install primary protection in lightning prone areas. To limit the over
26、voltage to 1.5 kV for the majority of di/dt expected to occur, in the case of a direct strike to the premises or to one of the services, requires good earthing and bonding techniques. This Recommendation includes how the responsibilities for protection are shared between the service provider and the
27、 customer. Generally, the overvoltage protection has been required for terminal equipment that has been traditionally under the network operators responsibility. Due to liberalization in telecommunications, the customer may now own this type of equipment. Customer ownership is expected to extend to
28、even more types of equipment in the future. It is reasonable that the electromagnetic environment in the customers premises should be the major dimensioning factor for protection needs and not its ownership. The electromagnetic environment effect is, on one hand, dependent on the type and probabilit
29、y of the occurrence of the electromagnetic phenomena and, on the other hand, on the physical layout of the equipment installation. Effective protection requires that the service provider has access to an equipotential bonding bar (EBB) complying with IEC 60364-1 4 and this Recommendation. As some of
30、 the practices required to achieve good earthing and bonding are beyond the control of the telecommunication network operator, this Recommendation allocates responsibility to other parties, e.g., the building owner/occupier. It is clear that the electrical installations of buildings are a part of th
31、e protection for safety and are the responsibility of the building owner. Good earthing and bonding is usually easy to achieve in new buildings and is the main thrust of this Recommendation. For existing buildings, it may be difficult and expensive to upgrade the installation. In this case, alternat
32、ive methods of protecting the installation (customer and equipment) are provided in Annex B. ITU-T Rec. K.66 (12/2004) 1 ITU-T Recommendation K.66 Protection of customer premises from overvoltages 1 Scope This Recommendation: provides practices for installing protection at residential and commercial
33、 customers premises; is intended to comply with IEC 60364-5-54 6 or national standardizing bodies on a.c. power installations; is intended for use with new installations as well as for expansion and upgrading of existing installations; is intended to encourage planning for electromagnetic compatibil
34、ity and safety, which should include bonding and earthing arrangements that accommodate installation tests and diagnostics; is not intended to replace national regulations on bonding configurations and earthing. For telecommunication equipment resistibility requirements, see ITU-T Rec. K.21 17. Perm
35、issible levels of electromagnetic emissions are covered by CISPR 22 1, or by national regulations. Concerning the need for overvoltage protectors, see ITU-T Recs K.11 15, K.39 20, K.46 21, K.47 22 and IEC 62305-2 14. Concerning the need for a Lightning Protection System (LPS), see IEC 62305-2 14 and
36、 national regulations. This Recommendation is intended for customers buildings, including residential and commercial installations. This Recommendation is not mandatory but intends to promote best practice protection methods by operators and regulators. Areas subject to a.c. earth potential rise (EP
37、R), e.g., substations may require additional protection measures, see Directives Volume VII and VIII. 2 References The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publicati
38、on, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the cu
39、rrently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. 1 CISPR 22 Ed. 3.0 b (1997), Information technology equipment Radio disturbance characteristics Limits and m
40、ethods of measurement. 2 IEC 60050, International Electrotechnical Vocabulary, Chapters 604 and 826. 3 IEC 61024, Protection of structures against lightning. 4 IEC 60364-1 (2001-08), Electrical installations of buildings Part 1: Fundamental principles, assessment of general characteristics, definiti
41、ons. 5 IEC 60364-4-44 (2003-12), Electrical installations of buildings Part 4 Chapter 44: Protection for safety Protection against voltage disturbances and electromagnetic 2 ITU-T Rec. K.66 (12/2004) disturbances Section 444: Protection against electromagnetic interferences (EMI) in installations of
42、 buildings. 6 IEC 60364-5-54 (2002-06), Electrical installations of buildings Part 5 Chapter 54: Selection and erection of electrical equipment Earthing arrangements, protective conductors and protective bonding conductors. 7 IEC 60950-1 (2001-10), Information technology equipment Safety Part 1: Gen
43、eral requirements. 8 IEC 61643-1 (2002-01), Surge protective devices connected to low-voltage power distribution systems Part 1: Performance requirements and testing methods. 9 IEC 61643-12 (2002-02), Low-voltage surge protective devices Part 12: Surge protective devices connected to low-voltage pow
44、er distribution systems Selection and application principles. 10 IEC 61643-21 (2000-09), Low-voltage surge protective devices Part 21: Surge protective devices connected to telecommunications and signalling networks Performance requirements and testing methods. 11 IEC 61643-22 (2004-11), Low-voltage
45、 surge protective devices Part 22: Surge protective devices connected to telecommunications and signalling networks Selection and application principles. 12 IEC 61663-2 (2001-03), Lightning protection Telecommunication lines Part 2: Lines using metallic conductors. 13 IEC/TR 62102 Ed.2, Electrical S
46、afety Classification of Interfaces for Equipment to be connected to Information and Communications Technology Networks. 14 IEC 62305-2 (draft) Ed. 1, Protection against lightning Part 2: Risk management. 15 ITU-T Recommendation K.11 (1993), Principles of protection against overvoltages and overcurre
47、nts. 16 ITU-T Recommendation K.12 (2000), Characteristics of gas discharge tubes for the protection of telecommunications installations. 17 ITU-T Recommendation K.21 (2003), Resistibility of telecommunication equipment installed in customer premises to overvoltages and overcurrents. 18 ITU-T Recomme
48、ndation K.27 (1996), Bonding configurations and earthing inside a telecommunication building. 19 ITU-T Recommendation K.31 (1993), Bonding configurations and earthing of telecommunication installations inside a subscribers building. 20 ITU-T Recommendation K.39 (1996), Risk assessment of damages to
49、telecommunication sites due to lightning discharges. 21 ITU-T Recommendation K.46 (2003), Protection of telecommunication lines using metallic symmetric conductors against lightning-induced surges. 22 ITU-T Recommendation K.47 (2000), Protection of telecommunication lines using metallic conductors against direct lightning discharges. 23 ITU-T Recommendation K.65 (2004), Overvoltage and overcurrent requirements for termination modules wi
