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.112 TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (12/2015) SERIES K: PROTECTION AGAINST INTERFERENCE Lightning protection, earthing and bonding: Practical procedures for radio base stations Recommendation ITU-T K.112 R
2、ec. ITU-T K.112 (12/2015) i Recommendation ITU-T K.112 Lightning protection, earthing and bonding: Practical procedures for radio base stations Summary Recommendation ITU-T K.112 provides a set of practical procedures related to the lightning protection, earthing and bonding of a radio base station
3、(RBS). It considers two types of RBS: those that are stand-alone installations, comprising a tower and the associated equipment and those that are installed on the roof of a building. In both cases, this Recommendation provides the procedures for the design and installation of the lightning air-term
4、ination system, down-conductors, earthing network, bonding conductors and surge protective devices (SPDs). This includes the specification of the materials, anti-corrosion protection and special treatment for rocky areas. Particular attention is directed to the protection of the navigation light sys
5、tems and of the electric power conductors that feed the RBS, especially in the case where the RBS is installed on the roof of a building. Annex A presents practical examples of earthing network design, whereas Annex B presents an overview of the techniques for measuring the earthing resistance and t
6、he earth resistivity. History Edition Recommendation Approval Study Group Unique ID* 1.0 ITU-T K.112 2015-12-14 5 11.1002/1000/12667 * 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, ht
7、tp:/handle.itu.int/11.1002/1000/11830-en. ii Rec. ITU-T K.112 (12/2015) 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 S
8、ector (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 Assembly (WTSA), which meets ev
9、ery 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 which fall within ITU-Ts purvi
10、ew, 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 this Recommendation is volun
11、tary. 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 language such as “must“ and th
12、e 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 this Recommendation may involve
13、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 of approval of this Recommen
14、dation, 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 the TSB patent database at ht
15、tp:/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.112 (12/2015) iii Table of Contents Page 1 Scope . 1 2 References . 1 3 Definitions 1 3.1 Terms defined elsewher
16、e 1 3.2 Terms defined in this Recommendation . 1 4 Abbreviations and acronyms 2 5 Conventions 2 6 Lightning protection and earthing of tower RBS . 3 6.1 Earthing network of a tower site 3 6.2 External lightning protection system 6 6.3 Earthing and bonding network outside equipment room . 10 6.4 Bond
17、ing configuration inside the equipment room 11 6.5 Protection of the navigation light system . 14 6.6 Protection of AC power supplies at the tower 15 7 Lightning protection, earthing and bonding of a rooftop RBS . 17 7.1 Earthing network 18 7.2 Down-conductors of a rooftop RBS . 18 7.3 Air-terminati
18、on system of buildings . 19 7.4 Rooftop bonding network . 21 7.5 Bonding configuration inside the equipment room 22 7.6 The equipment room in the building 22 7.7 Protection of AC power supplies of a rooftop RBS . 23 8 Circuit diagram and current capability of Class I/II SPD . 24 8.1 SPD configuratio
19、n for three-phase AC power supply 24 8.2 SPD configuration solution for two-phase AC power supply 24 8.3 SPD configuration for single-phase AC power supply 25 8.4 Specification of SPDs . 26 Annex A Example of earthing network design of a tower site . 27 A.1 Example where additional earthing electrod
20、es are necessary 27 A.2 Example where additional earthing electrodes are not necessary 27 Annex B Earthing resistance and soil resistivity test guide 29 B.1 General requirements for measurement 29 B.2 Four-point method for the measurement of earthing resistivity . 30 B.3 Three-point method for the m
21、easurement of earthing resistance . 31 B.4 Single clamp / double clamp method for the measurement of earthing resistance 32 Bibliography. 35 Rec. ITU-T K.112 (12/2015) 1 Recommendation ITU-T K.112 Lightning protection, earthing and bonding: Practical procedures for radio base stations 1 Scope This R
22、ecommendation addresses the practical procedures concerning the lightning protection, earthing and bonding of radio base station (RBS) sites. The purpose of this Recommendation is to give detailed guidance on protection procedures, so that an engineer who is not a lightning protection expert can acc
23、omplish the design of the lightning protection, earthing and bonding of an RBS by following the guidelines contained in this Recommendation. 2 References The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this R
24、ecommendation. 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 re
25、ferences 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. IEC 61643-11 IEC 61643-11 (2011), Low-voltage surge protective device
26、s Part 11: Surge protective devices connected to low-voltage power distribution systems Requirements and test methods. IEC 61643-12 IEC 60143-12 (2008), Low-voltage surge protective devices - Part 12: Surge protective devices connected to low-voltage power distribution systems - Selection and applic
27、ation principles. IEC 62305-2 IEC 62305-2 (2010), Protection against lightning Part 2: Risk management. IEC 62305-3 IEC 62305-3 (2010), Protection against lightning Part 3: Physical damage to structures and life hazard. 3 Definitions 3.1 Terms defined elsewhere This Recommendation uses the following
28、 terms defined elsewhere: 3.1.1 equipotential bonding b-ITU-T K.27: Electrical connection putting various exposed conductive parts and extraneous conductive parts at a substantially equal potential. 3.1.2 earthing network b-ITU-T K.27: The part of an earthing installation that is restricted to the e
29、arth electrodes and their interconnections. 3.2 Terms defined in this Recommendation This Recommendation defines the following terms: 3.2.1 air-termination system: Part of an external LPS using metallic elements such as rods, mesh conductors or catenary wires intended to intercept lightning flashes.
30、 3.2.2 down-conductor: Part of an external LPS intended to conduct lighting currents between the air-termination system and earth termination system. 2 Rec. ITU-T K.112 (12/2015) 3.2.3 lightning protection system (LPS): Complete system used to reduce physical damage due to lightning flashes to a str
31、ucture. NOTE An LPS consists of both external and internal lightning protection system. 3.2.4 navigation light control box (NLCB): The box that controls the light on the tower to warn pilots of airplanes about the presence of the tower. 4 Abbreviations and acronyms This Recommendation uses the follo
32、wing abbreviations and acronyms: ACDB Alternating Current Distribution Board ATS Automatic Transfer Switch BR Battery Return EMC Electromagnetic Compatibility LED Light Emitting Diode LPL Lightning Protection Level LPS Lightning Protection System MET Main Earthing Terminal MTS Manual Transfer Switch
33、 NL Navigation Light NLCB Navigation Light Control Box PDB Power Distribution Box PE Protective Earth PMB Power Meter Box RBS Radio Base Station SPD Surge Protective Device 5 Conventions The keywords “is required to“ indicate a requirement which must be strictly followed and from which no deviation
34、is permitted if conformance to this Recommendation is to be claimed. The keywords “is recommended“ indicate a requirement which is recommended but which is not absolutely required. Thus this requirement need not be present to claim conformance. The keywords “is prohibited from“ indicate a requiremen
35、t which must be strictly followed and from which no deviation is permitted if conformance to this Recommendation is to be claimed. The keywords “can optionally“ indicate an optional requirement which is permissible, without implying any sense of being recommended. This term is not intended to imply
36、that the vendors implementation must provide the option and the feature can be optionally enabled by the network operator/service provider. Rather, it means the vendor may optionally provide the feature and still claim conformance with this Recommendation. Rec. ITU-T K.112 (12/2015) 3 6 Lightning pr
37、otection and earthing of tower RBS 6.1 Earthing network of a tower site The most important objective of the radio base station (RBS) earthing network is to minimize the differences in potential between the conductive parts within the RBS site (equipotential bonding), which is beneficial for the safe
38、ty, lightning protection and electromagnetic compatibility (EMC) performance of the equipment. In order to achieve this, a ring loop shall surround the tower, the equipment room and the fence. The earthing resistance of an RBS is not very important, but an RBS with a low earthing resistance minimize
39、s the surge current that goes outwards from the RBS through the metallic services connections (such as power lines and telecommunication lines with metallic elements), when lightning strikes the tower. Therefore, whenever it is feasible, the RBS earthing resistance should be as low as 10 . Alternati
40、vely, instead of achieving a low earthing resistance value, a minimum earthing network mean radius should be achieved. 6.1.1 Mean radius of an RBS earthing network The earthing network of an RBS should be formed by a ring loop surrounding the tower, equipment room and fence, at a minimum. The mean r
41、adius re of this ring loop should be not less than l1, as indicated in Figure 1 and this value depends on the lightning protection system (LPS) class and on the soil resistivity. Class III or IV LPS may be suitable for a regular tower site. Alternatively, the user can define the LPS class by carryin
42、g out a risk assessment according to IEC 62305-2. When the LPS class has been determined, the user can define the value of earthing network mean radius according to Figure 1. The minimum required ring loop area Sm can be calculated by the equation below: sm = l12 (1) If the ring loop area Sr of the
43、RBS earthing network is smaller than the required minimum ring loop area Sm, additional earthing electrodes should be added. The mean value re corresponding to Sr can be calculated by the equation below: = (2) The required minimum length of additional earthing electrode lr (horizontal) or lv (vertic
44、al) is given by the following equation: lr = l1 re (3) lv = (l1 re)/2 (4) The additional earthing electrode is recommended to be added at the four corners of the ring loop and the minimum number of electrodes is four. Figure 2 shows an example of an RBS earthing network. Annex A provides an example
45、of how to design the earthing network when re is less than l1, as indicated in Figure 1. 4 Rec. ITU-T K.112 (12/2015) Figure 1 Minimum radius l1 of ring loop according to the class of LPS 6.1.2 The structure of an RBS earthing network A ring loop surrounding the RBS fence is recommended and the four
46、 legs of a metallic tower shall be connected to the ring loop by means of short buried conductors. The four corners of the equipment room shall also be connected to the ring by short conductors, when the equipment room is metallic or has steel-reinforced foundations, as shown in Figure 2. An additio
47、nal horizontal conductor shall be installed across the ring, between the equipment room and the tower and the earthing terminal at the feeder entrance window shall be connected to this conductor (see Figure 2). Figure 2 Earthing network of the RBS The ring loop shall be in contact with the earth for
48、 at least 80% of its total length. The earthing electrode should preferably be buried at a depth of at least 0.7 m and at a distance of about 1 m from the external walls of the equipment room. The top of the vertical rods shall be connected to the four corners of the ring loop (see Figure 2). Rec. I
49、TU-T K.112 (12/2015) 5 6.1.3 The earthing material The earthing electrodes could be made of copper, tin plated copper, copper coated steel, hot-dipped galvanized steel, or stainless steel. Table 1, adapted from IEC 62305-3, shows the main characteristics of the earthing electrodes. Table 1 Material, configuration and minimum dimensions of earth electrodes Material Configuration Dimensions Earth rod diameter mm Earth conductor mm2 Earth plate mm Copper Tin plated copper Stranded 50 Solid round 15 50 Solid tape
