1、 International Telecommunication Union ITU-T K.85TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (11/2011) SERIES K: PROTECTION AGAINST INTERFERENCE Requirements for the mitigation of lightning effects on home networks installed in customer premises Recommendation ITU-T K.85 Rec. ITU-T K.85 (11/2011
2、) i Recommendation ITU-T K.85 Requirements for the mitigation of lightning effects on home networks installed in customer premises Summary Recommendation ITU-T K.85 gives the requirements for home network equipment and installations in customer premises. It covers the classification of interfaces, r
3、esistibility of equipment, impact of installation practices, installation of surge protective devices (SPDs) and a risk assessment of equipment damage according to IEC 62305-2. The risk assessment of user injury will be covered by a separate Recommendation. History Edition Recommendation Approval St
4、udy Group 1.0 ITU-T K.85 2011-11-13 5 ii Rec. ITU-T K.85 (11/2011) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector
5、 (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 telecommunications on a worldwide basis. The World Telecommunication Standardization Assembly (WTSA), which meets every f
6、our 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 procedure laid down in WTSA Resolution 1. In some areas of information technology which fall within ITU-Ts purview, t
7、he 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 telecommunication administration and a recognized operating agency. Compliance with this Recommendation is voluntary.
8、 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 mandatory provisions are met. The words “shall“ or some other obligatory language such as “must“ and the neg
9、ative 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 draws attention to the possibility that the practice or implementation of this Recommendation may involve the
10、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 or others outside of the Recommendation development process. As of the date of approval of this Recommendati
11、on, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at http:/
12、www.itu.int/ITU-T/ipr/. ITU 2012 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. Rec. ITU-T K.85 (11/2011) iii Table of Contents Page 1 Scope 1 2 References. 1 3 Definitions 2 3.1 Terms defined elsewhere 2 3.2
13、Terms defined in this Recommendation . 3 4 Abbreviations and acronyms 3 5 Lightning damage . 3 6 Requirements 4 6.1 Classification of ports . 4 6.2 Resistibility . 5 6.3 Safety 6 6.4 Earthing 6 6.5 Risk assessment 6 6.6 Installation of overvoltage protection . 7 6.7 Wiring installation 8 6.8 Special
14、 requirements 8 6.9 Use of wireless and optical fibre 8 Annex A Principles of surge protection 9 A.1 Surge coupling into external telecommunication lines 9 A.2 Surge coupling into internal cabling . 9 A.3 Impact of actual installations 9 A.4 Separate earth electrodes 10 A.5 Philosophy of protection
15、. 10 Annex B Installation practices which may result in damage 11 Annex C Coordination 12 C.1 Telecommunication SPD coordination . 12 C.2 Mains SPD coordination . 13 C.3 Internal port coordination . 14 Annex D Risk assessment . 15 D.1 Explanation of terms . 15 D.2 Risk management . 18 Appendix I Ris
16、k assessment example . 21 I.1 General . 21 I.2 Building characteristics 22 I.3 Characteristics of the services 22 I.4 Characteristics of the internal systems . 23 I.5 Zones definition in the structure . 25 iv Rec. ITU-T K.85 (11/2011) Page I.6 Expected dangerous events to the structure 25 I.7 Risk a
17、ssessment for the unprotected structure 25 I.8 Selected protection measures . 27 I.9 Risk assessment related to the protected structure . 27 I.10 SPDs . 28 Appendix II Assessment of protection needs 29 II.1 Single port equipment . 29 II.2 Earthed equipment 29 II.3 Non-earthed equipment 29 II.4 Level
18、 of protection provided by an MSPD . 29 II.5 Consideration of loop areas 30 Bibliography. 32 Rec. ITU-T K.85 (11/2011) v Introduction This Recommendation provides all requirements to minimize disruption and damage to home networks. To ensure a reliable home network service it is essential that a num
19、ber of interrelated requirements are met. These include the following. All equipment complies with the appropriate resistibility level of ITU-T K.21. The equipment ports have been correctly classified in accordance with ITU-T K.75. Overvoltage protection, when required, has been installed according
20、to ITU-T K.66. This includes the use of both multiservice surge protective devices (MSPDs) and primary (point of entry) protection. It also includes ensuring correct earthing and bonding. A risk assessment of equipment damage is performed in accordance with IEC 62305-2. Rec. ITU-T K.85 (11/2011) 1 R
21、ecommendation ITU-T K.85 Requirements for the mitigation of lightning effects on home networks installed in customer premises 1 Scope This Recommendation applies to home networks installed in customer premises. Service to the home network can be provided by optical fibre, wireless, hybrid fibre/coax
22、ial (HFC) cable or x digital subscriber line (xDSL). This Recommendation predicts the frequency of damage to the home network (telecommunications) equipment within the structure. NOTE Consideration of loss of the telecommunication service is contained in ITU-T K.72. Consideration of injury of the se
23、rvice user, within the structure, will be considered in a future ITU-T Recommendation. 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 publication, the edition
24、s 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 currently valid I
25、TU-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. ITU-T K.12 Recommendation ITU-T K.12 (2010), Characteristics of gas discharge tubes for the protection of telecommunication
26、s installations. ITU-T K.21 Recommendation ITU-T K.21 (2008), Resistibility of telecommunication equipment installed in customer premises to overvoltages and overcurrents. ITU-T K.44 Recommendation ITU-T K.44 (2008), Resistibility tests for telecommunication equipment exposed to overvoltages and ove
27、rcurrents Basic Recommendation. ITU-T K.65 Recommendation ITU-T K.65 (2004), Overvoltage and overcurrent requirements for termination modules with contacts for test ports or SPDs. ITU-T K.66 Recommendation ITU-T K.66 (2004), Protection of customer premises from overvoltages. ITU-T K.67 Recommendatio
28、n ITU-T K.67 (2006), Expected surges on telecommunications and signalling networks due to lightning. ITU-T K.71 Recommendation ITU-T K.71 (2011), Protection of customer antenna installations. ITU-T K.72 Recommendation ITU-T K.72 (2011), Protection of telecommunication lines using metallic conductors
29、 against lightning Risk management. ITU-T K.75 Recommendation ITU-T K.75 (2008), Classification of interface for application of standards on resistibility and safety of telecommunication equipment. IEC 60364-4-44 IEC 60364-4-44 ed. 2 (2007), Low-voltage electrical installations Part 4-44: Protection
30、 for safety Protection against voltage disturbances and electromagnetic disturbances. 2 Rec. ITU-T K.85 (11/2011) IEC 60950-1 IEC 60950-1 ed. 2 (2005), Information technology equipment Safety Part 1: General requirements. IEC 61643-21 IEC 61643-21 ed. 1.1 Consol. with am1 (2009), Low-voltage surge p
31、rotective devices Part 21: Surge protective devices connected to telecommunications and signalling networks Performance requirements and testing methods. IEC 61643-22 IEC 61643-22 ed. 1 (2004), Low-voltage surge protective devices Part 22: Surge protective devices connected to telecommunications and
32、 signalling networks Selection and application principles. IEC 62305-2 IEC 62305-2 ed. 2 (2010), Protection against lightning Part 2: Risk management. IEC 62368-1 IEC 62368-1 ed. 1 (2010), Audio/video, information and communication technology equipment Part 1: Safety requirements. 3 Definitions 3.1
33、Terms defined elsewhere This Recommendation uses the following terms defined elsewhere: 3.1.1 home network b-ISO/IEC 15044: Internal network for digital and analogue information transport in home or business premises of similar complexity, providing defined access points and using any medium in any
34、topology. 3.1.2 level b-ETSI ES 201 468: Measures on a relative scale how important it is that the equipment operates as specified. NOTE Two levels are defined for the purpose of the present document and are designated as level 1 and level 2. Level 1 should be selected if the equipment has moderate
35、failure consequences. Equipment has moderate failure consequences when: a failure causes limited inconvenience; repairs may be made without compromising the responsibilities of the network operator. Level 2 should be selected if the equipment has severe failure consequences. Equipment has severe fai
36、lure consequences when: failure compromises the function of vital, centralized systems, or services of a commercially sensitive or security related nature; repair or restoration costs are high, or the time the equipment is out of service is unacceptably long; corruption of charging or billing inform
37、ation occurs. Rec. ITU-T K.85 (11/2011) 3 3.2 Terms defined in this Recommendation This Recommendation defines the following terms: 3.2.1 multiservice surge protective device (MSPD): A surge protective device (SPD) containing both telecommunications and mains protection. It may also include port pro
38、tection for video or Ethernet. 3.2.2 tracer/locate wire (optical fibre cable): Conductive wire in an optical fibre cable that allows a buried cable to be located with a metal detector. 4 Abbreviations and acronyms This Recommendation uses the following abbreviations and acronyms: CLP Cell Loss Prior
39、ity CPE Customer Premises Equipment GDT Gas Discharge Tube HFC Hybrid Fibre/Coaxial (cable) LEMP Lightning ElectroMagnetic Pulse LPS Lightning Protection System LT/NT Line Termination/Network Termination MET Main Earth Terminal MOV Metal-Oxide Varistor MSB Main electrical Switchboard MSPD Multiservi
40、ce Surge Protective Device NTD Network Termination Device PE Power Earth POTS Plain Old Telephone Service SELV Safety Extra-Low Voltage SPC Surge Protective Components SPD Surge Protective Device USB Universal Serial Bus xDSL Any of the various types of Digital Subscriber Lines 5 Lightning damage Da
41、mage to equipment can occur as a result of: surges entering on metallic services, with respect to the local earth; lightning strikes to antennas; lightning current entering the ground at or near the building with respect to remote earth; induction into indoor cabling due to nearby lightning. 4 Rec.
42、ITU-T K.85 (11/2011) 6 Requirements To limit the risk of misunderstanding by the supplier/manufacturer, it is recommended that the equipment specification for overvoltage protection and safety includes a schematic diagram showing the likely or possible applications of the equipment. This diagram sho
43、uld specifically address connections of the equipment within the building and especially its interconnection to any lines, or other equipment type connected to lines, that are external to the building. This should include any antenna connections. Some conditions might come with a small increase in i
44、tem cost but could significantly increase application and reduce life cycle cost. 6.1 Classification of ports ITU-T K.75 provides information on classifying plain old telephone service (POTS), Ethernet and video ports. A mains port is always an external port. Correct classification of ports is impor
45、tant. If an internal port is subject to conducted lightning surges or a.c. surges, there will be equipment damage and human safety issues. Please note that when specifying the above overvoltage and safety requirements it is also very important to clearly advise the vendors where the equipment is to
46、be used and what is expected to be connected to it (for example, whether it will or will not involve any connections to cabling that exits the building). Manufacturers of customer equipment in particular assume that the equipment ports will only be connected to intra-building cabling. A problem then
47、 occurs if the network operator, or the customer, decides to extend the service to an outbuilding. Equipment designed for connection to intra-building cabling may have insufficient isolation from the point of view of safety and insufficient resistibility to overvoltages, when connected to inter-buil
48、ding cables. To ensure the equipment use is not limited, the best way to proceed may be to assume that the port will connect to an inter-building cable, unless it is clear that it will not. The types of ports that could be connected to inter-building cabling include: POTS/xDSL; Ethernet; coaxial cab
49、le ports. For those ports that may connect to inter-building cables, classify the ports as follows: For IEC 60950-1 (safety) testing, use TNV-3 for ports with a working voltage higher than the safety extra-low voltage (SELV); or TNV-1 for ports with a working voltage lower than or equal to SELV (see IEC 60950-1 for definitions). For IEC 62368-1 (safety) testing the applicable value of the transient voltage on an external circuit shall be det
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