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.20 TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (07/2017) SERIES K: PROTECTION AGAINST INTERFERENCE Resistibility of telecommunication equipment installed in a telecommunication centre to overvoltages and overcurrents
2、Recommendation ITU-T K.20 Rec. ITU-T K.20 (07/2017) i Recommendation ITU-T K.20 Resistibility of telecommunication equipment installed in a telecommunication centre to overvoltages and overcurrents Summary Recommendation ITU-T K.20 specifies resistibility requirements and test procedures for telecom
3、munication equipment that is attached to or installed within a telecommunication centre. Overvoltages and overcurrents covered by this Recommendation include surges due to lightning on or near the line plant, short-term induction from adjacent a.c. power lines or railway systems, earth potential ris
4、e due to power faults, direct contact between telecommunication lines and power lines, and electrostatic discharges (ESDs). The sources for overvoltages in internal lines, between equipment or racks, are mainly inductive coupling caused by lightning currents being conducted in nearby lightning strik
5、es or lightning currents being conducted in nearby conductors. Major changes compared with Recommendation ITU-T K.20 (2008) include: updated references; added information on which universal serial bus (USB) ports should be tested; added information on when to add protection to untested ports; added
6、test requirements for external coaxial cable ports; added test requirements for multiple conductor internal unshielded cable ports. Major changes compared with Recommendation ITU-T K.20 (2011) include: added test requirements for unshielded twisted pair Ethernet (UTPE); added test requirements for s
7、hielded twisted pair Ethernet (STPE); added test requirements for power over Ethernet (PoE); added STPE shield testing. History Edition Recommendation Approval Study Group Unique ID* 1.0 ITU-T K.20 1984-10-19 11.1002/1000/6964 2.0 ITU-T K.20 1988-11-25 11.1002/1000/1387 3.0 ITU-T K.20 1991-03-18 V 1
8、1.1002/1000/1388 4.0 ITU-T K.20 1993-03-12 V 11.1002/1000/1389 5.0 ITU-T K.20 1996-10-18 5 11.1002/1000/3880 6.0 ITU-T K.20 2000-02-25 5 11.1002/1000/4904 7.0 ITU-T K.20 2003-07-29 5 11.1002/1000/6492 7.1 ITU-T K.20 (2003) Amd. 1 2004-11-12 5 11.1002/1000/7499 8.0 ITU-T K.20 2008-04-13 5 11.1002/100
9、0/9400 9.0 ITU-T K.20 2011-11-13 5 11.1002/1000/11420 10.0 ITU-T K.20 2015-04-22 5 11.1002/1000/12403 11.0 ITU-T K.20 2016-06-29 5 11.1002/1000/12867 12.0 ITU-T K.20 2016-12-14 5 11.1002/1000/13126 13.0 ITU-T K.20 2017-07-29 5 11.1002/1000/13272 Keywords 1.2/50-8/20, 10/700, Ethernet, external ports
10、, internal port, overvoltage, overcurrent, power over Ethernet (PoE), power contact, power induction, resistibility, subscriber line integrated circuit, SLIC, surges, telecommunication equipment, telecommunication centres, transverse, universal serial bus, USB. * To access the Recommendation, type t
11、he URL http:/handle.itu.int/ in the address field of your web browser, followed by the Recommendations unique ID. For example, http:/handle.itu.int/11.1002/1000/11830-en. ii Rec. ITU-T K.20 (07/2017) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in
12、 the field of telecommunications, information and communication technologies (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 st
13、andardizing telecommunications 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
14、 covered by the procedure 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
15、indicate both a telecommunication 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 ac
16、hieved when all of these 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. INTELLECTU
17、AL PROPERTY RIGHTSITU draws 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
18、asserted by ITU members 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, implementers are cautio
19、ned that this may not represent the latest information and are therefore 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 IT
20、U. Rec. ITU-T K.20 (07/2017) iii Table of Contents Page 1 Scope . 1 2 References . 1 3 Definitions 1 3.1 Terms defined elsewhere 1 3.2 Terms defined in this Recommendation . 2 4 Abbreviations and acronyms 2 5 Conventions 2 6 Tests 2 Appendix I Floating transverse power induction and earth potential
21、rise test for ports connected to external symmetric pair cables 27 I.1 Introduction 27 I.2 Discussion of the reason for the damage 27 I.3 Test set-up and test voltages . 28 Bibliography. 29 Rec. ITU-T K.20 (07/2017) 1 Recommendation ITU-T K.20 Resistibility of telecommunication equipment installed i
22、n a telecommunication centre to overvoltages and overcurrents 1 Scope This Recommendation specifies resistibility requirements and test procedures for equipment installed in a telecommunication centre where the earthing, bonding and cabling between equipment or racks is in accordance with ITU-T K.27
23、. This Recommendation applies to both external and internal ports. ITU-T K.44 is an integral part of this Recommendation and should be read in conjunction with ITU-T K.11, ITU-T K.39 and ITU-T K.46. This Recommendation applies to all telecommunication equipment, whether network operator or customer
24、owned, including telephony, routers and modems. It does not apply to equipment such as personal computers or printers. 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
25、time of publication, 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.
26、 A list of the currently 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. ITU-T K.11 Recommendation ITU-T K.11 (2009), Principles of protection against overvoltages
27、and overcurrents. ITU-T K.27 Recommendation ITU-T K.27 (2015), Bonding configurations and earthing inside a telecommunication building. ITU-T K.39 Recommendation ITU-T K.39 (1996), Risk assessment of damages to telecommunication sites due to lightning discharges. ITU-T K.44 Recommendation ITU-T K.44
28、 (2017), Resistibility tests for telecommunication equipment exposed to overvoltages and overcurrents Basic Recommendation. ITU-T K.46 Recommendation ITU-T K.46 (2012), Protection of telecommunication lines using metallic symmetric conductors against lightning-induced surges. IEC 61000-4-2 IEC 61000
29、-4-2:2008, Electromagnetic compatibility (EMC) Part 4-2: Testing and measurement techniques Electrostatic discharge immunity test. 3 Definitions 3.1 Terms defined elsewhere This Recommendation uses the following terms defined elsewhere: 3.1.1 dedicated power feed (dpf) ITU-T K.44. 3.1.2 IT power dis
30、tribution system ITU-T K.44. 3.1.3 TT power distribution system ITU-T K.44. 2 Rec. ITU-T K.20 (07/2017) 3.2 Terms defined in this Recommendation None. 4 Abbreviations and acronyms This Recommendation uses the following abbreviations and acronyms: CWG Combination Wave Generator ESD Electrostatic Disc
31、harge PoE Power over Ethernet SLIC Subscriber Line Integrated Circuit SPD Surge Protective Device STP Special Test Protector STPE Shielded Twisted Pair Ethernet USB Universal Serial Bus UTPE Unshielded Twisted Pair Ethernet Other definitions, abbreviations, conventions and symbols used in this Recom
32、mendation are defined in ITU-T K.44. 5 Conventions None. 6 Tests A summary of the tests applicable to equipment installed in a telecommunication centre is given in Table 1. The numbers given in the “Port type“ columns, e.g., 2.2.1a, refer to the “Test no.“ of Tables 2 to 5. The words “under study“ m
33、ean that ITU-T is still studying this test. The test conditions applicable to the four ports: symmetric, coaxial, dedicated power feed and mains power are given in Tables 2 to 5. The test conditions for electrostatic discharge (ESD) are given in Table 6. The test conditions for internal cable ports
34、are given in Table 7. For information on the headings and terms used in the tables, refer to clause 10 of ITU-T K.44. Refer to clause 5.2 of ITU-T K.44 on selecting the enhanced resistibility requirement. NOTE 1 For small telecommunication centres, the resistance of the earth electrode may be signif
35、icantly high. When the “enhanced“ requirement is specified, and the centre has 250 symmetric pairs or fewer, apply the port to the external port test from b-ITU-T K.45, but retain the inherent test voltages from this Recommendation. NOTE 2 The external port test applies to ports used to connect exte
36、rnally-attached equipment to equipment installed within the same building. The mains power contact test does not apply in this situation. Where the equipment external to the building is installed in the “inherently protected“ area shown in Figure 3 of b-ITU-T K.71 the internal port test can be appli
37、ed. NOTE 3 The power induction test does not apply to ports used to connect to antennas installed within the scope of b-ITU-T K.71. NOTE 4 The internal port tests in Table 7 apply to ports connected by short cables, e.g., universal serial bus (USB) and printer cables. Table 7 does not apply to ports
38、 connected infrequently, e.g., for maintenance ports. Rec. ITU-T K.20 (07/2017) 3 Table 1a Applicable tests for external ports Test type No. of pairs simultaneously tested Test connection Primary protection Port type Symmetric port Coaxial port Dedicated power feed port Mains power port Lightning vo
39、ltage Single Transverse/ differential No 2.1.1a 3.1.1 4.1.1a 5.1.1a Port to earth No 2.1.1b n/a 4.1.1b 5.1.1b Port to external port No n/a n/a 4.1.1c 5.1.1c Coordination/ Transverse/ differential Yes 2.1.2a 3.1.2 4.1.2a 5.1.2a Coordination/Port to earth Yes 2.1.2b n/a 4.1.2b 5.1.2b Coordination/Port
40、 to external port Yes 2.1.2c n/a 4.1.2c 5.1.2c Multiple Port to earth No 2.1.3a n/a n/a n/a Port to external port No 2.1.3b n/a n/a n/a Port to earth Yes 2.1.4a n/a n/a n/a Port to external port Yes 2.1.4b n/a n/a n/a Unshielded twisted pair (UTPE) Ethernet Port to earth No 2.1.8 n/a n/a n/a Transve
41、rse No 2.1.7 n/a n/a n/a Voltage impulse test No 2.1.10 n/a n/a Power over Ethernet (PoE) No 2.1.11 n/a n/a Shielded twisted pair (STPE) Ethernet Port to earth No 2.1.8 n/a n/a Shield to earth No 2.1.9, n/a n/a Lightning current Single Port to earth No 2.1.5a n/a 4.1.5a n/a Port to external port No
42、n/a n/a n/a n/a Differential n/a n/a 3.1.3 n/a n/a Shield to earth n/a n/a 3.1.4 n/a n/a Shield to external port n/a n/a 3.1.5 n/a n/a Multiple Port to earth No 2.1.6a n/a n/a n/a Port to external port No n/a n/a n/a n/a Single Transverse No 2.2.1a Under study 4.2.1a n/a 4 Rec. ITU-T K.20 (07/2017)
43、Table 1a Applicable tests for external ports Test type No. of pairs simultaneously tested Test connection Primary protection Port type Symmetric port Coaxial port Dedicated power feed port Mains power port Port to earth No 2.2.1b n/a 4.2.1b 5.2.1 under study Power induction and earth potential rise
44、Port to external port No 2.2.1c n/a 4.2.1c n/a Coordination Transverse Yes 2.2.2a Under study 4.2.2a n/a Coordination Port to earth Yes 2.2.2b n/a 4.2.2b n/a Coordination Port to external port Yes 2.2.2c n/a 4.2.2c n/a Neutral potential rise Single Port to earth No n/a n/a n/a 5.2.2a Port to externa
45、l port No n/a n/a n/a 5.2.2b Mains power contact Single Transverse No 2.3.1a n/a 4.3.1a n/a Port to earth No 2.3.1b n/a 4.3.1b n/a Port to external port No 2.3.1c n/a 4.3.1c n/a Rec. ITU-T K.20 (07/2017) 5 Table 1b Lightning test conditions for ports connected to internal cables No. of pairs simulta
46、neously tested Test connection Primary protection Unshielded cable Shielded cable PoE power feed Floating DC powering Earthed DC powering Single Shielded cable to earth No 7.2 USB shielded cable to earth No 7.3 STPE Ethernet simultaneous port to earth No 7.4 UTPE/STPE Ethernet transverse No 7.7 7.7
47、Earthed d.c. power interface No 7.9 Multiple Unshielded cable with symmetric pairs No 7.1 PoE Mode A and Mode B transverse testing No 7.5 UTPE Ethernet port rated impulse voltage No 7.6 Floating d.c. power interface No 7.8 6 Rec. ITU-T K.20 (07/2017) Table 2a Lightning test conditions for ports conn
48、ected to external symmetric pair cables Test no. Test description Test circuit and waveform (see figures in Annex A of ITU-T K.44) Basic test levels (also see clause 7 of ITU-T K.44) Enhanced test levels (also see clauses 5 and 7 of ITU-T K.44) Number of tests Primary protection (clause 8 of ITU-T K
49、.44) Acceptance criteria (clause 9 of ITU-T K.44) Comments 2.1.1a Single pair, lightning, inherent, transverse A.3-1 and A.6.1-1 (a and b) 10/700 Uc(max) = 1.0 kV R = 25 Uc(max) = 1.5 kV R = 25 Alterna-ting 5 surges (60 s between success-ive surges) None A This test does not apply when the equipment is designed to always be used with primary protection and the operator agrees. If this test does not apply, perform the appropriate test from Table 7. When the equipment c
