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 (06/2016) 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 (06/2016) 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 or 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 rise
4、 due to power faults, direct contact between telecommunication lines and power lines and electrostatic discharges. The sources for overvoltages in internal lines, between equipment/racks, are mainly inductive coupling caused by lightning currents being conducted in nearby lightning strokes or lightn
5、ing currents being conducted in nearby conductors. Major changes compared with the 2008 version of this Recommendation 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 test
6、requirements for external coaxial cable ports; added test requirements for multiple conductor internal unshielded cable ports. Major changes compared with the 2011 version of this Recommendation include: added test requirements for unshielded twisted pair (UTP) Ethernet; added test requirements for
7、shielded twisted pair STP Ethernet; added test requirements for power over Ethernet (PoE); added STP 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 11.1
8、002/1000/1388 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 11.1002/1000/9
9、400 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 Keywords 1.2/50-8/20, 10/700, Ethernet, external ports, internal port, overvoltage, overcurrent, power over Ethernet (PoE), power contact, power inductio
10、n, resistibility, subscriber line integrated circuit, SLIC, surges, telecommunication equipment, telecommunication centres, transverse, universal serial bus, USB. * To access the Recommendation, type the URL http:/handle.itu.int/ in the address field of your web browser, followed by the Recommendati
11、ons unique ID. For example, http:/handle.itu.int/11.1002/1000/11830-en. ii Rec. ITU-T K.20 (06/2016) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Teleco
12、mmunication 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 Telecommunication Standardization As
13、sembly (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 of information technology w
14、hich 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 operating agency. Compliance with
15、 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“ or some other obligatory l
16、anguage 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 practice or implementation of thi
17、s 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 development process. As of the date
18、 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 strongly urged to consult
19、the TSB patent database at http:/www.itu.int/ITU-T/ipr/. ITU 2016 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.20 (06/2016) iii Table of Contents Page 1 Scope . 1 2 References . 1 3 Definitions
20、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 rise test for ports connected to external symmetric pair cables 25 I.1 Introduction 25 I.2 Discussi
21、on on the reason for the damages 25 I.3 Test set-up and test voltages . 26 Bibliography. 27 Rec. ITU-T K.20 (06/2016) 1 Recommendation ITU-T K.20 Resistibility of telecommunication equipment installed in a telecommunication centre to overvoltages and overcurrents 1 Scope This Recommendation specifie
22、s resistibility requirements and test procedures for equipment installed in a telecommunication centre where the earthing, bonding and cabling between equipment/racks is in accordance with ITU-T K.27. This Recommendation applies to both external and internal ports. ITU-T K.44 is an integral part of
23、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 owned, including telephony, routers and modems, etc. It does not apply to personal computers and prin
24、ters, etc. 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 Recommendations and other references are subject
25、 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 published. The reference to a document wit
26、hin 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 and overcurrents. ITU-T K.27 Recommendation ITU-T K.27 (2015), Bonding configurations and earthing inside a
27、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 (2016), Resistibility tests for telecommunication equipment exposed to overvoltages and overcurrents Basic
28、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 61000-4-2 (2008), Electromagnetic compatibility (EMC) Part 4-2: Testing and measurement techniques Electrostatic
29、discharge immunity test. 3 Definitions 3.1 Terms defined elsewhere This Recommendation uses the following terms defined elsewhere: 3.1.1 IT power distribution system ITU-T K.44. 3.1.2 TT power distribution system ITU-T K.44. 2 Rec. ITU-T K.20 (06/2016) 3.2 Terms defined in this Recommendation None.
30、4 Abbreviations and acronyms This Recommendation uses the following abbreviations and acronyms: CWG Combination Wave Generator ESD Electrostatic Discharge PoE Power over Ethernet SLIC Subscriber Line Integrated Circuit STP Shielded Twisted Pair USB Universal Serial Bus UTP Unshielded Twisted Pair Ot
31、her definitions, abbreviations, conventions and symbols used in this Recommendation 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
32、.2.1a, refer to the “Test no.“ of Tables 2 to 5. The words “under study“ mean 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
33、 (ESD) are given in Table 6. The test conditions for internal cable ports 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 tele
34、communication centres, the resistance of the earth electrode may be significantly 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 Recommend
35、ation. NOTE 2 The external port test applies to ports used to connect externally-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“
36、area shown in Figure 3 of b-ITU-T K.71 the internal port test can be applied. NOTE 3 The power induction test does not apply to ports used to connect to antennas installed under 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., unive
37、rsal serial bus (USB) and printer cables. Table 7 does not apply to ports connected infrequently, e.g., for maintenance ports. Rec. ITU-T K.20 (06/2016) 3 Table 1a Applicable tests for external ports Test type No. of pairs simultaneously tested Test connection Primary protection Port type Symmetric
38、port Coaxial port Dedicated power feed port Mains power port Lightning voltage 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 5.1.2
39、a Coordination/Port to earth Yes 2.1.2b n.a. 4.1.2b 5.1.2b Coordination/Port 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
40、. n.a. Unshielded twisted pair (UTP) Ethernet Port to earth No n.a. n.a. n.a. n.a. Transverse No 2.1.7 n.a. n.a. n.a. Voltage impulse test No 2.1.9 2.1.9 n.a. n.a. Power over Ethernet (PoE) No 2.1.10 2.1.10 n.a. n.a. Shielded twisted pair (STP) Ethernet Port to earth No 2.1.8 2.1.8 n.a. n.a. Shield
41、test No 2.1.11 2.1.11 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 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
42、.1.6a n.a. n.a. n.a. Port to external port No n.a. n.a. n.a. n.a. Insulation Multiple Port to earth n.a. 2.1.9, 7.6 n.a. n.a. n.a. 4 Rec. ITU-T K.20 (06/2016) Table 1a Applicable tests for external ports Test type No. of pairs simultaneously tested Test connection Primary protection Port type Symmet
43、ric port Coaxial port Dedicated power feed port Mains power port Power induction and earth potential rise Single Transverse No 2.2.1a Under study 4.2.1a n.a Port to earth No 2.2.1b n.a. 4.2.1b 5.2.1 under study Port to external port No 2.2.1c n.a. 4.2.1c n.a. Coordination Transverse Yes 2.2.2a Under
44、 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 external port No n.a. n.a. n.a. 5.2.2b Mains power contact Single Transverse No 2.3.1a
45、 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. Table 1b Applicable tests for internal ports Test type Primary protection Unshielded cable Shielded cable PoE Floating d.c. power interface Earthed d.c. power interface Lightning No 7.1, 7.6, 7
46、.7 7.2, 7.3, 7.4, 7.6, 7.7 7.5 7.7 7.8 5 Rec. ITU-T K.20 (06/2016) Table 2a Lightning test conditions for ports connected 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) E
47、nhanced test levels (also see clauses 5 and 7 of ITU-T K.44) Number of tests Primary protection ITU-T K.44, clause 8) Acceptance criteria ITU-T K.44, clause 9) Comments 2.1.1a Single pair, lightning, inherent, transverse A.3-1 and A.6.1-1 (a and b) 10/700 s Uc(max) = 1.0 kV R = 25 Uc(max) = 1.5 kV R
48、 = 25 alternating 5 surges (60 seconds between successive 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 contains high
49、 current-carrying components which eliminate the need for primary protection, this test does not apply. (lower voltage level testing also required for each test see clause 7.3 of ITU-T K.44) 2.1.1b Single pair, lightning, inherent, port to earth A.3-1 and A.6.1-2 10/700 s Uc(max) = 1.0 kV R = 25 Uc(max) = 1.5 kV R = 25 2.1.1c Single pair, lightning, inherent, port to external port A.3-1 and A.6.1-3 10/700 s n.a. n.a. 2.1.2a Single pair, lightning, coordination, transverse
