1、 I n t e r n a t i o n a l T e l e c o m m u n i c a t i o n U n i o n ITU-T K.118 TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (12/2016) SERIES K: PROTECTION AGAINST INTERFERENCE Requirements for lightning protection of fibre to the distribution point equipment Recommendation ITU-T K.118 Rec. IT
2、U-T K.118 (12/2016) i Recommendation ITU-T K.118 Requirements for lightning protection of fibre to the distribution point equipment Summary Recommendation ITU-T G.9701 specifies a gigabit broadband access technology that exploits the existing infrastructure of wire pairs that were originally deploye
3、d for plain old telephone service (POTS) services. Equipment implementing this Recommendation can be deployed from fibre to the distribution point (FTTdp) located very near the customers premises. Recommendation ITU-T K.118 contains the necessary information to enable the protection of a distributio
4、n point (DP) node in the access network and the associated equipment in the customers premises. It includes information on the resistibility requirements of the equipment, the rating of the lightning protection, when the installation of protection is necessary and on how to install this protection.
5、History Edition Recommendation Approval Study Group Unique ID* 1.0 ITU-T K.118 2016-12-14 5 11.1002/1000/13134 Keywords EPR, GDT, lightning protection, MOVs, MSPDs, power contact and SPDs. * To access the Recommendation, type the URL http:/handle.itu.int/ in the address field of your web browser, fo
6、llowed by the Recommendations unique ID. For example, http:/handle.itu.int/11.1002/1000/11830-en. ii Rec. ITU-T K.118 (12/2016) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technolo
7、gies (ICTs). 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 telecommunications on a worldwide basis. The World Telecommu
8、nication 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 procedure laid down in WTSA Resolution 1. In some areas
9、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 telecommunication administration and a recognized operat
10、ing 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 mandatory provisions are met. The words “shall“
11、 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 RIGHTSITU draws attention to the possibility that the practi
12、ce 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 or others outside of the Recommendation developm
13、ent 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, implementers are cautioned that this may not represent the latest information and are therefore
14、 strongly urged to consult the TSB patent database at http:/www.itu.int/ITU-T/ipr/. ITU 2017 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.118 (12/2016) iii Table of Contents Page 1 Scope . 1 2 R
15、eferences . 1 3 Definitions 2 3.1 Terms defined elsewhere 2 3.2 Terms defined in this Recommendation . 2 4 Abbreviations and acronyms 2 5 Conventions 3 6 Elements of protection 3 6.1 Correct classification and use of ports 4 6.2 Equipment design considerations . 4 6.3 Equipment resistibility 6 6.4 P
16、rimary protection and MSPDs 6 6.5 Requirements for earthing and bonding . 7 6.6 Risk assessment 7 6.7 Responsibility . 8 6.8 A.C. earth potential rise (EPR) . 8 Appendix I Level of protection . 9 I.1 Protection against surges induced into external cables 9 I.2 Protection against direct strikes to th
17、e power or telecommunications cables or lines more than 100 m away from the DPU 9 I.3 Protection against direct strikes 9 Bibliography. 10 iv Rec. ITU-T K.118 (12/2016) Introduction Fibre to the distribution point (FTTdp) supports one or more high-speed copper drops into customer premises and uses a
18、 gigabit (or faster) fibre link to backhaul user data to a high order node (HON). A key aspect of the new node type is the ability for it to be reverse power fed from one or more copper drop pairs. To reverse power feed (RPF), there needs to be power supply functionality at the customers premises. T
19、o this end a new node type, the distribution point unit (DPU), is defined. This node is typically positioned at the distribution point (DP). To maintain the reliability of the network it is necessary to ensure that this equipment has the required level of resistibility and that the necessary lightni
20、ng protection is installed when needed. Rec. ITU-T K.118 (12/2016) 1 Recommendation ITU-T K.118 Requirements for lightning protection of fibre to the distribution point (FTTdp) equipment 1 Scope This Recommendation applies to the equipment installed at the distribution point (DP) node and the associ
21、ated equipment installed at the customers premises. 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 editions indicated were valid. All Recomme
22、ndations 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 ITU-T Recommendations is regularly p
23、ublished. 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 telecommunications installations. ITU-T K.21 Recomme
24、ndation ITU-T K.21 (2016), Resistibility of telecommunication equipment installed in customer premises to overvoltages and overcurrents. ITU-T K.35 Recommendation ITU-T K.35 (1996), Bonding configurations and earthing at remote electronic sites. ITU-T K.44 Recommendation ITU-T K.44 (2016), Resistibi
25、lity tests for telecommunication equipment exposed to overvoltages and overcurrents Basic Recommendation. ITU-T K.45 Recommendation ITU-T K.45 (2016), Resistibility of telecommunication equipment installed in the access and trunk networks to overvoltages and overcurrents. ITU-T K.65 Recommendation I
26、TU-T K.65 (2011), Overvoltage and overcurrent requirements for termination modules with contacts for test ports or surge protective devices. ITU-T K.66 Recommendation ITU-T K.66 (2011), Protection of customer premises from overvoltages. ITU-T K.75 Recommendation ITU-T K.75 (2016), Classification of
27、interface for application of standards on resistibility and safety of telecommunication equipment. ITU-T K.85 Recommendation ITU-T K.85 (2011), Requirements for the mitigation of lightning effects on home networks installed in customer premises. ITU-T K.98 Recommendation ITU-T K.98 (2014), Overvolta
28、ge protection guide for telecommunication equipment installed in customer premises. ITU-T K.108 Recommendation ITU-T K.108 (2015), Joint use of poles by telecommunication and solidly earthed power lines. ITU-T K.109 Recommendation ITU-T K.109 (2015), Installation of telecommunication equipment on ut
29、ility poles. IEC 60950-1 IEC 60950-1:2005+AMD1:2009+AMD2:2013 CSV, Information technology equipment Safety Part 1: General requirements. 2 Rec. ITU-T K.118 (12/2016) IEC 61643-311 IEC 61643-331:2013, Components for low-voltage surge protective devices Part 311: Performance requirements and test circ
30、uits for gas discharge tubes (GDT). IEC 61643-331 IEC 61643-331:2003, Components for low-voltage surge protective devices Part 331: Specification for metal oxide varistors (MOV). IEC 62305-2 IEC 62305-2 Ed. 2.0 (2010), Protection against lightning Part 2: Risk management. IEC 62368-1 IEC 62368-1 Ed.
31、 2.0 (2014), Audio/video, information and communication technology equipment Part 1: Safety requirements. 3 Definitions 3.1 Terms defined elsewhere This Recommendation uses the following terms defined elsewhere: 3.1.1 high current carrying protection components ITU-T K.44: A high current carrying pr
32、otection component is an SPD which, when activated by the surge, conducts/diverts the majority of the surge away from the circuit it is protecting. High current carrying protection components are mainly used as primary protection components, but in some cases may be integrated into the equipment as
33、inherent protection. 3.1.2 inherent protection ITU-T K.44: Inherent protection is protection that is provided within the equipment either by virtue of its intrinsic characteristics, by specific design, or by suitable protection components. 3.1.3 primary protection ITU-T K.44: Means by which the majo
34、rity of the surge stress is prevented from propagating beyond a designated location (preferably the building entrance point). 3.1.4 spark-overvoltage ITU-T K.12: The voltage which causes spark-over when applied across the terminals of a gas discharge tube. 3.2 Terms defined in this Recommendation Th
35、is Recommendation defines the following term: 3.2.1 thermal protection: integral switch function of a surge protective component (SPC) that operates when the component temperature exceeds a pre-set value. NOTE 1 A thermally protected gas discharge tube (GDT) has a normally open thermal switch connec
36、ted in parallel with the electrodes, which shorts out the GDT when the component temperature exceeds a pre-set value. NOTE 2 A thermally protected metal oxide varistor (MOV) has a normally closed thermal switch connected in series with MOV element, which disconnects the MOV when the component temper
37、ature exceeds a pre-set value. 4 Abbreviations and acronyms This Recommendation uses the following abbreviations and acronyms: a.c. alternating current d.c. direct current DP Distribution Point DPU Distribution Point Unit EPR Earth Potential Rise Rec. ITU-T K.118 (12/2016) 3 ES1 Electrical Energy So
38、urce class 1 ES2 Electrical Energy Source class 2 FTTdp Fibre To The distribution point GDT Gas Discharge Tube HON High Order Node MEB Main Electrical Board MOV Metal Oxide Varistor MSPD Multi-service Surge Protective Device PE Protective Earth RPF Reverse Power Feeding SELV Safety Extra Low Voltage
39、 SPC Surge Protective Component SPD Surge Protective Device VoIP Voice over Internet Protocol 5 Conventions None. 6 Elements of protection Fibre to the distribution point (FTTdp) supports one or more high-speed copper drops into customer premises and uses a gigabit (or faster) fibre link to backhaul
40、 user data to a high order node (HON). A key aspect of the new node type is the ability for it to be reverse power fed from one or more copper drop pairs. To reverse power feed (RPF), there needs to be power supply functionality at the customer premises. To this end a new node type, the distribution
41、 point unit (DPU), is defined. This node is typically positioned at the distribution point (DP). 4 Rec. ITU-T K.118 (12/2016) Figure 1 Fibre to the distribution point (FTTdp) There are many different methods of supplying the RPF to the FTTdp equipment at the DP. In some applications the modem signal
42、 will share the copper pair and in other applications separate pairs will be used. These options are described in b-ETSI TS 101 548. To ensure that adequate lightning protection is installed, or can be installed, it is necessary to consider a number of issues. These are: 1 correct classification and
43、 use of ports 2 equipment design considerations 3 equipment resistibility 4 primary protection 5 requirements for earthing and bonding 6 risk assessment 7 responsibility 8 A.C. earth potential rise (EPR). 6.1 Correct classification and use of ports Correct classification and use of ports: It is nece
44、ssary that the equipment ports have been correctly classified, designed and used in accordance with ITU-T K.75. For the RPF equipment installed in the customer premises both the mains and the power feed ports need to be external ports. For the DP equipment all ports need to be external ports. 6.2 Eq
45、uipment design considerations Where lightning protection above the inherent resistibility level of 1.5 kV is required, there are two options: Add primary protection outside the equipment when a risk assessment indicates that protection should be installed. Rec. ITU-T K.118 (12/2016) 5 Design the equ
46、ipment with integral high current carrying protection components (e.g., gas discharge tubes (GDTs) as part of the inherent protection. Typically, this is only implemented for access network equipment. In both cases the protection could be used as bypass protection or the protection could be earthed.
47、 Bypass and earthed protection is shown pictorially in Figure 2. Figure 2 Pictorial illustration of bypass and earthed protection 6.2.1 Floating equipment This is equipment that does not require a protective earth (PE) and it is powered from an SELV, ES1 or ES2 circuit, or has a double insulated pow
48、er supply. If the DPU will not be earthed it is a good idea to ensure that a flashover to earth is unlikely. A figure of 20 kV of isolation is probably a good figure to achieve. While it is possible for a telecommunications cable to conduct 100 kV surges, joints will break down at lower voltages. At
49、 the breakdown point of the joint an EPR will occur and the voltage on the cable can still be more than the breakdown voltage of the joint. The more joints that break down the lower the cable voltage will be. Further information on the surge voltage in a cable is provided in ITU-T K.98. ITU-T K.109 has additional requirements for installations on power poles. 6.2.2 Earthed equipment This equipment requires a PE connection. ITU-T K.109 has additional requirements for installations o
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