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.21 TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (06/2016) SERIES K: PROTECTION AGAINST INTERFERENCE Resistibility of telecommunication equipment installed in customer premises to overvoltages and overcurrents Recommend
2、ation ITU-T K.21 Rec. ITU-T K.21 (06/2016) i Recommendation ITU-T K.21 Resistibility of telecommunication equipment installed in customer premises to overvoltages and overcurrents Summary Recommendation ITU-T K.21 specifies resistibility requirements and test procedures for telecommunication equipme
3、nt that is attached to or installed within a customers premises. Overvoltages or overcurrents covered by this Recommendation include surges due to lightning on or near the line plant, short-term induction from adjacent alternating current (a.c.) power lines or railway systems, earth potential rise d
4、ue to power faults, direct contact between telecommunication lines and power lines, and electrostatic discharges. The sources for overvoltages in internal lines are mainly inductive coupling caused by lightning currents being conducted in nearby lightning strikes or lightning currents being conducte
5、d by nearby conductors. Major changes compared with the 2008 edition 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 requirements for external c
6、oaxial cable ports; added test requirements for multiple conductor internal unshielded cable ports. Major changes compared with the 2011 edition of this Recommendation include: added test requirements for unshielded twisted pair (UTP) Ethernet; added test requirements for shielded twisted pair (STP)
7、 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.21 1988-11-25 11.1002/1000/1390 2.0 ITU-T K.21 1996-10-18 5 11.1002/1000/3881 3.0 ITU-T K.21 2000-10-06 5 11.1002/1000/5153 4.0 ITU-T
8、 K.21 2003-07-29 5 11.1002/1000/6493 5.0 ITU-T K.21 2008-04-13 5 11.1002/1000/9401 6.0 ITU-T K.21 2011-11-13 5 11.1002/1000/11421 7.0 ITU-T K.21 2015-04-22 5 11.1002/1000/12404 8.0 ITU-T K.21 2016-06-29 5 11.1002/1000/12868 Keywords 1.2/50-8/20, 10/700, customer premises equipment, Ethernet, externa
9、l port, internal port, overvoltage, overcurrent, power over Ethernet (PoE), power contact, power induction, resistibility, surges, telecommunication equipment, transverse, universal serial bus (USB). * To access the Recommendation, type the URL http:/handle.itu.int/ in the address field of your web
10、browser, followed by the Recommendations unique ID. For example, http:/handle.itu.int/11.1002/1000/11830-en. ii Rec. ITU-T K.21 (06/2016) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communicatio
11、n 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 standardizing telecommunications on a worldwide basis. The World
12、 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 covered by the procedure laid down in WTSA Resolution 1. In s
13、ome 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 indicate both a telecommunication administration and a recogni
14、zed 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 achieved when all of these mandatory provisions are met. The wor
15、ds “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. INTELLECTUAL PROPERTY RIGHTSITU draws attention to the possibility that
16、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 asserted by ITU members or others outside of the Recommendatio
17、n 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 cautioned that this may not represent the latest information and are
18、 therefore strongly urged to consult 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.21 (06/2016) iii Table of Contents Page 1 Scop
19、e . 1 2 References . 1 3 Definitions 1 3.1 Terms defined elsewhere 1 3.2 Terms defined in this Recommendation . 1 4 Abbreviations, acronyms and symbols . 2 5 Conventions 2 6 Tests 2 Bibliography. 27 Rec. ITU-T K.21 (06/2016) 1 Recommendation ITU-T K.21 Resistibility of telecommunication equipment in
20、stalled in customer premises to overvoltages and overcurrents 1 Scope This Recommendation specifies resistibility requirements and test procedures for telecommunication equipment which is attached to or installed within a customers premises. The requirements of this Recommendation assume that earthi
21、ng and bonding is in accordance with ITU-T K.66. The types of equipment covered by this Recommendation include all types of telecommunication equipment, e.g., modems, telephones, routers, implementations of digital subscriber lines and personal computers. NOTE Associated equipment containing ports w
22、ith a low surge impedance to earth connected by short cables, e.g., printers using universal serial bus (USB) cables, may be susceptible to damage due to circulating earth currents. Refer to ITU-T K.66 and b-ITU-T K.85 for methods of protection. This Recommendation applies to both external and inter
23、nal ports. ITU-T K.44, covering basic test methods and test circuits, is an integral part of this Recommendation and should be read in conjunction with ITU-T K.11 and ITU-T K.39. 2 References The following ITU-T Recommendations and other references contain provisions which, through reference in this
24、 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 encouraged to investigate the possibility of applying the most recent editi
25、on 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 document, the status of a Recommendation. ITU-T K.11 Recommendation ITU-T
26、 K.11 (2009), Principles of protection against overvoltages and overcurrents. 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 equipme
27、nt exposed to overvoltages and overcurrents Basic Recommendation. ITU-T K.66 Recommendation ITU-T K.66 (2011), Protection of customer premises from overvoltages. IEC 61000-4-2 IEC 61000-4-2 (2008), Electromagnetic compatibility (EMC) Part 4-2: Testing and measurement techniques Electrostatic dischar
28、ge immunity test. 3 Definitions 3.1 Terms defined elsewhere This Recommendation uses terms defined in ITU-T K.44. 3.2 Terms defined in this Recommendation None. 2 Rec. ITU-T K.21 (06/2016) 4 Abbreviations, acronyms and symbols 4.1 Abbreviations and acronyms This Recommendation uses the following abb
29、reviations and acronyms: a.c. alternating current CWG Combination Wave Generator d.c. direct current ESD Electrostatic Discharge n.a. not applicable PoE Power over Ethernet STP Shielded Twisted Pair USB Universal Serial Bus UTP Unshielded Twisted Pair 4.2 Symbols This Recommendation uses the followi
30、ng symbols: f frequency I current R resistance t duration Ua.c. alternating current voltage Ua.c.(max) maximum alternating current voltage Uc charging voltage Uc(max) maximum charging voltage Urms root mean square voltage Wsp(max) maximum specific energy 5 Conventions Conventions and symbols used in
31、 this Recommendation are defined in ITU-T K.44. 6 Tests A summary of the tests applicable to equipment installed in a customers premises 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“ mean that ITU-T
32、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 are given in Tab
33、le 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 The port to external port test for the basic test level does not apply when the equipment is designed to
34、 always be used with a connection to earth. Rec. ITU-T K.21 (06/2016) 3 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 ext
35、ernal 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 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 test
36、s 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 connected infrequently, e.g., for maintenance ports. Table 1a Applicable tests for external ports Test type No. of pairs simultaneously tested Test connections
37、Primary protection Port type Symmetric port Co-axial 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 2.1.1c n.a. 4.1.1c 5.1.1c Coordination/Transverse/
38、 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 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
39、. Port to external port Yes 2.1.4b n.a. n.a. 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 a test No 2.1.10 n.a. n.a. n.a. Power over Ethernet (PoE) No 2.1.9 n.a. n.a. n.a. Shielded twisted pair (STP) shield Shield
40、 to earth No 2.1.11 2.1.11 n.a. n.a. Port to earth No 2.1.8 2.1.8 n.a. n.a. 4 Rec. ITU-T K.21 (06/2016) Table 1a Applicable tests for external ports Test type No. of pairs simultaneously tested Test connections Primary protection Port type Symmetric port Co-axial port Dedicated power feed port Mains
41、 power port Lightning current Single Port to earth No 2.1.5a n.a. 4.1.5a n.a. Port to external port No 2.1.5b n.a. 4.1.5b n.a. Multiple Port to earth No 2.1.6a, 2.1.10 n.a. n.a. n.a. Port to external port No 2.1.6b 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
42、 n.a. n.a. Shield to external port n.a. n.a. 3.1.5 n.a. n.a. Insulation Multiple Port to earth n.a. 2.1.10, 7.6 n.a. n.a. n.a. Power induction and earth potential rise Single Transverse No 2.2.1a Understudy 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
43、.1c n.a. 4.2.1c 5.2.1 under study Coordination Transverse Yes 2.2.2a Understudy 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
44、 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. n.a.: not applicable. Table 1b Applicable tests for ports connected to internal cabling Test type Primary protection Un
45、shielded cable Shielded cable PoE Floating d.c. power interface Earthed d.c. power interface Lightning No 7.1, 7.6, 7.2, 7.3, 7.4, 7.7 7.5 7.7 7.8 d.c.: direct current 5 Rec. ITU-T K.21 (06/2016) Table 2a Lightning test conditions for ports connected to external symmetric pair cables Test no. Test d
46、escription 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 (see clause 8 of ITU-T K.44) Acceptance criteria (see clause 9 of ITU-T K.4
47、4) 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) = 1.5 kV R = 25 Uc(max) = 1.5 kV R = 25 Alternating 5 surges (60 s between successive surges) None A Test 2.1.1 does not apply when the equipment is designed to always be used with primary pr
48、otection and the operator agrees. If this test is not performed, the appropriate test from Table 7 applies. If the inherent protection of the port under test contains surge protective devices (SPDs) that are connected to earth, a Uc(max) of 1.5 kV shall be used instead of 6 kV. If the equipment has
49、an insulated case, the 6 kV test is applied with the equipment wrapped in conductive foil and the foil is connected to the generator return. When the equipment contains high current-carrying components that 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) = 1.5 kV R = 25 Uc(max) =
