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 (04/2015) 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 (04/2015) 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 _ * To access the Recommendation, type the 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/
10、11830-en. ii Rec. ITU-T K.20 (04/2015) 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 (ITU-T) is a permanent orga
11、n 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 four years, establishes the t
12、opics 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, the necessary standards are p
13、repared 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. However, the Recommendation
14、 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 negative equivalents are used t
15、o 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 this Recommendation may involve the use of a claimed Intellectual
16、 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 Recommendation, ITU had not received noti
17、ce 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:/www.itu.int/ITU-T/ipr/. ITU 2
18、015 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 (04/2015) 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 Reco
19、mmendation . 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 26 I.1 Introduction 26 I.2 Discussion on the reason for the damages 26 I.3 Test set-up and test v
20、oltages . 27 Bibliography. 28 Rec. ITU-T K.20 (04/2015) 1 Recommendation ITU-T K.20 Resistibility of telecommunication equipment installed in a telecommunication centre to overvoltages and overcurrents 1 Scope This Recommendation specifies resistibility requirements and test procedures for equipment
21、 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 this Recommendation and should be read in conjunction with ITU
22、-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 printers, etc. 2 References The following ITU-T Recommendations an
23、d 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 to revision; users of this Recommendation are therefore encou
24、raged 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 within this Recommendation does not give it, as a stand-alone doc
25、ument, 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 (1996), Bonding configurations and earthing inside a telecommunication building. ITU-T K.39 Recommendation ITU-T K.
26、39 (1996), Risk assessment of damages to telecommunication sites due to lightning discharges. ITU-T K.44 Recommendation ITU-T K.44 (2012), Resistibility tests for telecommunication equipment exposed to overvoltages and overcurrents Basic Recommendation. ITU-T K.46 Recommendation ITU-T K.46 (2012), P
27、rotection 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 discharge immunity test. 3 Definitions 3.1 Terms defined elsew
28、here 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 (04/2015) 3.2 Terms defined in this Recommendation None. 4 Abbreviations and acronyms This Recommendation uses the foll
29、owing 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 Other definitions, abbreviations, conventions and symbols used i
30、n 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., 2.2.1a, refer to the “Test no.“ of Tables 2 to 5. The words “un
31、der 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 (ESD) are given in Table 6. The test conditions for internal
32、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 telecommunication centres, the resistance of the earth electrode m
33、ay 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 Recommendation. NOTE 2 The external port test applies to ports used to
34、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“ area shown in Figure 3 of b-ITU-T K.71 the internal port test
35、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., universal serial bus (USB) and printer cables. Table 7 does not app
36、ly to ports connected infrequently, e.g., for maintenance ports. Rec. ITU-T K.20 (04/2015) 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 L
37、ightning 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 5.1.2a Coordination/Port to earth Yes 2.1.2b n.a. 4.1.2b 5.1.2b Coo
38、rdination/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. n.a. Unshielded twisted pair (UTP) Ethernet Port to earth No
39、 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 test No 2.1.11 2.1.11 n.a. n.a. Lightning current Single Port
40、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 2.1.6a n.a. n.a. n.a. Port to external port No n.a. n.a. n.a. n
41、.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 (04/2015) 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 po
42、rt 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 study 4.2.2a n.a. Coordination Port to earth Yes 2.2.2b n.a.
43、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 n.a. 4.3.1a n.a. Port to earth No 2.3.1b n.a. 4.3.1b n.a. Por
44、t 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, 7.7 7.2, 7.3, 7.4, 7.6, 7.7 7.5 7.7 7.8 5 Rec. ITU-T K.20 (04/2
45、015) 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) Enhanced test levels (also see clauses 5 and 7 of ITU-T K.44) N
46、umber 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 = 25 alternating 5 surges (60 seconds between successive surg
47、es) 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 current-carrying components which eliminate the need for prim
48、ary 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,
49、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 A.3-1 and A.6.1-1 (a and b) 10/700 s Uc(max) = 4 kV R = 25 Uc(max) = 4 kV R = 25 alternating 5 surges (60 seconds between successive surges) Special test protector; see clause 8.4 of ITU-T K.44. When performing the external port to external port test, also add an STP/primary protector to the untested port. A When the test is performe
