1、 International Telecommunication Union ITU-T K.51TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (07/2009) SERIES K: PROTECTION AGAINST INTERFERENCE Safety criteria for telecommunication equipmentRecommendation ITU-T K.51 Rec. ITU-T K.51 (07/2009) i Recommendation ITU-T K.51 Safety criteria for tele
2、communication equipment Summary Recommendation ITU-T K.51 provides guidance on safety criteria for telecommunication network infrastructure equipment. It specifies requirements intended to reduce risks of fire, electric shock or injury for the operator, layman and service personnel who may come into
3、 contact with the equipment. This Recommendation refers to IEC 60950-1 and provides additional requirements when these are not covered by IEC 60950-1. Equipment complying with the relevant requirements in this Recommendation is considered suitable for use in a telecommunication network. However, thi
4、s Recommendation does not include requirements for performance or functional characteristics of equipment. Source Recommendation ITU-T K.51 was approved on 14 July 2009 by ITU-T Study Group 5 (2009-2012) under Recommendation ITU-T A.8 procedures. Keywords Remote power feeding, safety, telecommunicat
5、ion equipment. ii Rec. ITU-T K.51 (07/2009) 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
6、 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 Assembly (WTSA), which meets every four years, establishes
7、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 which fall within ITU-Ts purview, the necessary standards
8、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 this Recommendation is voluntary. However, the Recommend
9、ation 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 us
10、ed to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. INTELLECTUAL PROPERTY RIGHTS ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intelle
11、ctual 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
12、 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 the TSB patent database at http:/www.itu.int/ITU-T/ipr/.
13、ITU 2010 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.51 (07/2009) iii CONTENTS Page 1 Scope 1 1.1 Equipment covered by this Recommendation 1 1.2 Additional requirements . 1 2 References. 1 3 De
14、finitions 2 4 Abbreviations 2 5 Safety criteria for telecommunication network infrastructure equipment 2 5.1 General requirements 2 5.2 Special requirements 2 Appendix I Cross-reference between Recommendation ITU-T K.51 and IEC 60950-1 6 iv Rec. ITU-T K.51 (07/2009) Introduction This Recommendation
15、provides guidance on safety criteria for telecommunication network infrastructure equipment. The requirements of this Recommendation have been developed in cooperation with IEC TC108. This Recommendation should be read together with IEC 60950-1. Rec. ITU-T K.51 (07/2009) 1 Recommendation ITU-T K.51
16、Safety criteria for telecommunication equipment 1 Scope 1.1 Equipment covered by this Recommendation This Recommendation is applicable to mains-powered, battery-powered or remotely-powered telecommunication network infrastructure equipment. This Recommendation specifies requirements intended to redu
17、ce risks of fire, electric shock, mechanical hazards or injury for the operator and layman who may come into contact with the equipment and, where specifically stated, for service personnel. This Recommendation is intended to reduce such risks with respect to installed equipment, whether it consists
18、 of a system of interconnected units or independent units, subject to installing, operating and maintaining the equipment in the manner prescribed by the manufacturer. Equipment complying with the relevant requirements in this Recommendation is considered suitable for use in a telecommunication netw
19、ork. However, this Recommendation does not include requirements for performance or functional characteristics of equipment. 1.2 Additional requirements Requirements additional to those specified in this Recommendation may be necessary for: equipment intended for operation in special environments, fo
20、r example, extremes of temperature; excessive dust, moisture or vibration; flammable gases; and corrosive or explosive atmospheres; equipment intended to be used in vehicles, on board ships or aircraft, in tropical countries, or at altitudes greater than 2000 m; equipment intended for use where ingr
21、ess of water is possible. NOTE Attention is drawn to the fact that authorities of some countries impose additional requirements. 2 References The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendatio
22、n. 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 edition of the Recommendations and other references lis
23、ted 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.50 Recommendation ITU-T K.50 (2000), Safe limits of operating voltages an
24、d currents for telecommunication systems powered over the network. IEC 60950-1 IEC 60950-1 (2005), Information technology equipment Safety Part 1: General requirements. IEC 60950-21 IEC 60950-21 (2002), Information technology equipment Safety Part 21: Remote power feeding. NOTE This Recommendation r
25、efers to IEC 60950-1, but the related concepts or requirements of IEC 60950 are still applicable in countries where IEC 60950 is still used. 2 Rec. ITU-T K.51 (07/2009) 3 Definitions In this Recommendation, the definitions introduced by ITU-T K.50, IEC 60950-1 and IEC 60950-21 are used. As it is rec
26、ommended to read these documents together, the definitions are not reproduced here. 4 Abbreviations This Recommendation uses the following abbreviations: RFT Remote Feeding Telecommunication circuit RFT-C Remote Feeding Telecommunication circuit-Current limited RFT-V Remote Feeding Telecommunication
27、 circuit-Voltage limited SELV Safety Extra Low Voltage TNV Telecommunication Network Voltage 5 Safety criteria for telecommunication network infrastructure equipment 5.1 General requirements Telecommunication network infrastructure equipment shall comply with all the relevant requirements of IEC 609
28、50-1 and IEC 60950-21. 5.2 Special requirements Remote feeding telecommunication circuits (RFT circuits) are defined in both ITU-T K.50 and IEC 60950-21. For RFT circuits the requirements in clauses 5.2.1, 5.2.2, 5.2.3 and 5.2.6 apply. The requirements for openings in telecommunication network infra
29、structure equipment are described in IEC 60950-1; however, the existing requirements do not restrict the entry of vermin or geckos. For enclosure openings, the requirements of clauses 5.2.5 and 5.2.6 apply. For the readers convenience, a cross-reference, between the requirements of this Recommendati
30、on and similar paragraphs of IEC 60950-1 is provided in Appendix I. 5.2.1 Protection from electric shock and energy hazards 5.2.1.1 Access to energized parts The equipment shall be so constructed that in user access areas, there is adequate protection against contact with bare parts of RFT circuits.
31、 5.2.1.2 Protection in service access areas Bare parts at hazardous voltages, except for RFT circuits, shall be located or guarded so that unintentional contact with such parts is unlikely during service operations involving other parts of the equipment. Bare parts at hazardous voltage, including RF
32、T circuits, shall be located or guarded so that accidental shorting to SELV circuits or to TNV circuits, for example by tools or test probes used by service personnel, is unlikely. 5.2.1.3 Protection in restricted access locations For equipment to be installed in a restricted access location, contac
33、t is permitted with the bare parts of RFT circuits by the test finger as defined in Figure 2A of IEC 60950-1. However, such parts shall be so located or guarded that unintentional contact is unlikely. Rec. ITU-T K.51 (07/2009) 3 5.2.2 Interconnection of equipment 5.2.2.1 General requirements Where e
34、quipment is intended to be electrically connected to other equipment, interconnection circuits shall be selected to provide continued conformance to the requirements of ITU-T K.50 for RFT circuits, after making the connections. NOTE 1 This is normally achieved by connecting RFT-C circuits to RFT-C c
35、ircuits and RFT-V circuits to RFT-V circuits. NOTE 2 It is permitted for an interconnecting cable to contain more than one type of circuit (e.g., SELV, limited current, TNV, ELV, RFT, or hazardous voltage) provided that they are separated as required by this Recommendation and IEC 60950-1. 5.2.2.2 T
36、ypes of interconnecting circuits An RFT can be an interconnection circuit. 5.2.2.3 Interconnection between RFT circuits The interconnection of one RFT-V circuit to another RFT-V circuit shall not result in exceeding the limits specified in Annex A of ITU-T K.50. The interconnection of one RFT-C circ
37、uit to another RFT-C circuit shall not result in exceeding the limits specified in Annex B of ITU-T K.50. 5.2.3 Protection of telecommunication network service personnel, and users of other equipment connected to the network, from hazards in the equipment 5.2.3.1 Protection from hazardous voltages C
38、ircuitry intended to be directly connected to a telecommunication network shall comply with the requirements of an SELV circuit, a TNV circuit or an RFT circuit. 5.2.4 Separation from other circuits and parts An RFT circuit shall be separated from: other RFT circuits by functional isolation; provide
39、d that neither circuit exceeds the limits of ITU-T K.50 if this isolation is short-circuited. Otherwise, the circuits shall be separated as if one were at a hazardous voltage; ELV circuits by supplementary insulation; earthed accessible parts, earthed SELV circuits and earthed TNV circuits by basic
40、insulation; unearthed accessible parts, unearthed SELV circuits, unearthed TNV circuits and circuits at hazardous voltages by one or both of the following: double or reinforced insulation; basic insulation, together with protective screening connected to the main protective earthing terminal. Compli
41、ance is checked by inspection and measurement. 5.2.5 Preventing vermin ingress Vermin ingress can have a number of adverse effects such as: Biting or stinging of service personnel; Causing faults in the equipment; Causing a fire in the equipment. 4 Rec. ITU-T K.51 (07/2009) Equipment enclosure holes
42、 or openings are restricted in size, by IEC 60950-1, to prevent hazardous contact with energized circuitry. This is verified by the use of a jointed test finger, pin and probe such as described in IEC 60950-1, Figures 2A, 2B and 2C, respectively. The test pin has the smallest diameter. An enclosure
43、opening smaller than 3 mm will prevent test pin entry. Circular or mesh openings of 3 mm or less will also prevent the entry of most common stinging insects such as: honey bees, bumble bees, yellow jackets, bald-faced hornets, European hornets, and some other solitary wasp species. Only very small i
44、nsects, such as 1 mm long fire ants, can still enter through a 3 mm hole and establish nests. Ground level and subterranean enclosures are particularly vulnerable to ant infestation. Mounting the enclosure above ground, on a pole or to the side of a building reduces the risk of infestation. Enclosur
45、es designed to prevent the entry of rain and dust further reduce the risk of ant infestation. 5.2.6 Installation instructions For equipment using an RFT circuit intended for interconnection with other equipment, the installation instructions shall specify all of the following: the effective capacita
46、nce of the equipment: between the connection points for the conductors of the telecommunication network; and between the connection point for one conductor of the telecommunication network and earth; that a system assessment shall be carried out to ensure that the effective capacitance of the total
47、system, including the capacitance of the equipment, does not exceed the values specified in Figure 1; that the voltage rating of the telecommunication network must be adequate for the normal RFT circuit voltage, together with any superimposed transient; RFT circuit voltage. For equipment with enclos
48、ure holes or openings, the installation instructions shall specify detailed installation requirements for preventing vermin or gecko entry, e.g., installation location, safeguard methods. Rec. ITU-T K.51 (07/2009) 5 Figure 1 Limits for capacitance values of RFT circuits or of the total system 6 Rec.
49、 ITU-T K.51 (07/2009) Appendix I Cross-reference between Recommendation ITU-T K.51 and IEC 60950-1 (This appendix does not form an integral part of this Recommendation) For the readers convenience, this appendix provides a cross-reference between the requirements of this Recommendation and paragraphs of IEC 60950-1 where similar requirements for other circuits are given (Table I.1). Table I.1 K.51 clause number IEC 60950-1 paragraph number 5.2.1.1 2.1.1.15.2.1.2 2.1.2 5.2.1.3 2.1
