ITU-T K 56 CORR 1-2017 Protection of radio base stations against lightning discharges Corrigendum 1 (Study Group 5).pdf

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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.56 TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU Corrigendum 1 (07/2017) SERIES K: PROTECTION AGAINST INTERFERENCE Protection of radio base stations against lightning discharges Corrigendum 1 Recommendation ITU-T K.56 (

2、2010) Corrigendum 1 Rec. ITU-T K.56 (2010)/Cor.1 (07/2017) i Recommendation ITU-T K.56 Protection of radio base stations against lightning discharges Corrigendum 1 Summary Recommendation ITU-T K.56 presents the techniques applied to a telecommunication radio base station in order to protect it again

3、st lightning discharges. The need of protection is obtained from the methodology contained in IEC 62305-2, which is used to determine the relevant lightning protection level (LPL) for the installation. The protection techniques for the external area cover the lightning protection system (LPS), bondi

4、ng procedures, earthing and the installation of surge protective devices (SPDs) at the power meter station. The protection techniques for the equipment building cover the feeder and lighting cables, the electric power conductors, the telecommunication cabling and the earthing/bonding procedures appl

5、ied to cable trays and equipment frames. This Recommendation also provides guidelines in order to achieve adequate protection of the telecommunication equipment based on the coordination between equipment resistibility, SPD protection level and installation characteristics. Corrigendum 1 to Recommen

6、dation ITU-T K.56 (2010) deletes the factor “2“ in the denominator given in Equation 7 (clause 8.1). History Edition Recommendation Approval Study Group Unique ID* 1.0 ITU-T K.56 2003-07-29 5 11.1002/1000/6500 2.0 ITU-T K.56 2010-01-13 5 11.1002/1000/10443 2.1 ITU-T K.56 (2010) Cor. 1 2017-07-29 5 1

7、1.1002/1000/13275 _ * 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/11.1002/1000/11830-en. ii Rec. ITU-T K.56 (2010)/Cor.1 (07/2017) FOREWORD The International Te

8、lecommunication 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 organ of ITU. ITU-T is responsible for studying technical, operating and

9、 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 topics for study by the ITU-T study groups which, in turn, produce Re

10、commendations 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 prepared on a collaborative basis with ISO and IEC. NOTE In this Reco

11、mmendation, 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 may contain certain mandatory provisions (to ensure e.g., interoper

12、ability 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 to express requirements. The use of such words does not suggest that c

13、ompliance 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 Property Right. ITU takes no position concerning the evidence, valid

14、ity 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 notice of intellectual property, protected by patents, which may be requi

15、red 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 2017 All rights reserved. No part of this publication may be reproduce

16、d, by any means whatsoever, without the prior written permission of ITU. Rec. ITU-T K.56 (2010)/Cor.1 (07/2017) iii Table of Contents Page 1 Scope and purpose 1 2 References . 1 3 Definitions 2 4 Abbreviations and acronyms 2 5 Need of protection 2 6 External area . 3 6.1 Lightning protection system

17、(LPS) 3 6.2 Bonding in the tower 4 6.3 Earthing 7 6.4 Power meter station 8 7 Equipment building 9 7.1 Feeder and lighting cables 9 7.2 Power conductors . 11 7.3 Telecommunication conductors 14 7.4 Earthing and bonding of metallic elements 16 8 Protection of RBS equipment . 18 8.1 Inductive voltage

18、drop across the SPD connecting leads . 20 8.2 Voltage induced in the internal cabling 20 Annex A Shielding factor () of cable trays . 22 Annex B Shielding factor () of building walls 24 Annex C Example of earthing and bonding configuration inside an RBS . 25 Appendix I Results of tests with rocket-t

19、riggered lightning on a radio base station 26 I.1 Introduction 26 I.2 Description of the test site 26 I.3 Recordings of the lightning current 27 I.4 Shielding factor of tower and feeder tray . 27 I.5 Bonding the feeder to the tower at ground level 28 I.6 Current flowing through service conductors 29

20、 I.7 Inductive voltage drop in the SPD connecting leads 30 Bibliography. 31 Rec. ITU-T K.56 (2010)/Cor.1 (07/2017) 1 Recommendation ITU-T K.56 Protection of radio base stations against lightning discharges Corrigendum 1 Editorial note: This is a complete-text publication. Modifications introduced by

21、 this corrigendum are shown in revision marks relative to Recommendation ITU-T K.56 (2010). 1 Scope and purpose This Recommendation addresses radio base stations (RBSs) made of a shelter or small building to house the equipment and a nearby tower to hold the antennas. The purpose of this Recommendat

22、ion is to provide a set of procedures to protect the RBS against lightning discharges. ITU-T K.71 gives information on the protection of antenna installations in or on a customer building. 2 References The following ITU-T Recommendations and other references contain provisions which, through referen

23、ce 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 encouraged to investigate the possibility of applying the most re

24、cent 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 document, the status of a Recommendation. ITU-T K.12 Recommenda

25、tion ITU-T K.12 (2006), Characteristics of gas discharge tubes for the protection of telecommunications installations. ITU-T K.27 Recommendation ITU-T K.27 (1996), Bonding configurations and earthing inside a telecommunication building. ITU-T K.35 Recommendation ITU-T K.35 (1996), Bonding configurat

26、ions and earthing at remote electronic sites. ITU-T K.44 Recommendation ITU-T K.44 (2008), Resistibility tests for telecommunication equipment exposed to overvoltages and overcurrents Basic Recommendation. ITU-T K.46 Recommendation ITU-T K.46 (2008), Protection of telecommunication lines using metal

27、lic symmetric conductors against lightning-induced surges. ITU-T K.47 Recommendation ITU-T K.47 (2008), Protection of telecommunication lines using metallic conductors against direct lightning discharges. ITU-T K.66 Recommendation ITU-T K.66 (2004), Protection of customer premises from overvoltages.

28、 ITU-T K.71 Recommendation ITU-T K.71 (2007), Protection of customer antenna installations. ITU-T K.72 Recommendation ITU-T K.72 (2008), Protection of telecommunication lines using metallic conductors against lightning Risk management. IEC 61643-1 IEC 61643-1 (2005), Low-voltage surge protective dev

29、ices Part 1: Surge protective devices connected to low-voltage power distribution systems Requirements and tests. 2 Rec. ITU-T K.56 (2010)/Cor.1 (07/2017) IEC 61643-11 IEC 61643-11 (2004), Low-voltage surge protective devices Part 11: Surge protective devices connected to low-voltage power distribut

30、ion systems Performance requirements and testing methods. IEC 61643-12 IEC 61643-12 (2008), Low-voltage surge protective devices Part 12: Surge protective devices connected to low-voltage power distribution systems Selection and application principles. IEC 61643-22 IEC 61643-22 (2004), Low-voltage s

31、urge protective devices Part 22: Surge protective devices connected to telecommunications and signalling networks Selection and application principles. IEC 62305-1 IEC 62305-1 (2006), Protection against lightning Part 1: General principles. IEC 62305-2 IEC 62305-2 (2006), Protection against lightnin

32、g Part 2: Risk management. IEC 62305-3 IEC 62305-3 (2006), Protection against lightning Part 3: Physical damage to structures and life hazard. 3 Definitions The definitions contained in the references apply to this Recommendation. Additional definitions needed for the protection of radio base statio

33、ns (RBSs) are as follows: 3.1 cable tray: Rigid structural system used to securely fasten or support cables. 3.2 feeder cable: Wave-guide or coaxial cable that conducts signals to an antenna. 3.3 lightning protection system (LPS) rod: Metallic rod that makes part of the LPS and is intended to interc

34、ept a lightning strike. It is also designated as “lightning air termination“ or “lightning finial“. 3.4 radio base station: Installation intended to provide access to the telecommunication system by means of radio waves. 3.5 shielding factor: Factor that represents the attenuation of the voltage or

35、current in a conductor due to the presence of a nearby shielding conductor. 3.6 single-pulse peak current: Rated maximum current value which may be applied for a single impulse of specified waveshape, without causing surge protective device (SPD) failure. Typically, this rating is defined using eith

36、er an 8/20 or 10/350 impulse current waveshape. 4 Abbreviations and acronyms This Recommendation uses the following abbreviations and acronyms: GDT Gas Discharge Tube LPL Lightning Protection Level LPS Lightning Protection System MEB Main Earthing Bar PE Protective Earth RBS Radio Base Station SPD S

37、urge Protective Device Rec. ITU-T K.56 (2010)/Cor.1 (07/2017) 3 5 Need of protection The risk assessment of the RBS shall be performed according to IEC 62305-2 in order to determine a lightning protection level (LPL) for the design of the protection procedures. Table 1 shows some lightning flash par

38、ameters associated with each LPL. Table 1 Lightning flash parameters from IEC 62305-1 Parameter Unit LPL I II III IV Maximum peak current kA 200 150 100 100 Maximum current rate of rise kA/s 200 150 100 100 Radius of electro-geometric sphere m 20 30 45 60 Probability of flash % 99 98 95 90 NOTE The

39、risk assessment may indicate an LPL for the design of the LPS that is different from the LPL considered for the design of the other protection procedures. 6 External area Figure 1 shows the main earthing and bonding procedures applied to the external area. These procedures, as well as others not sho

40、wn in the figure, are detailed in the subsequent clauses. 6.1 Lightning protection system (LPS) In order to protect the antennas and auxiliary equipment from a direct strike, it may be necessary to install an LPS in the tower. If the nearby tower does not protect the shelter, it may be necessary to

41、install an LPS in the shelter too. The assessment of the need for an LPS and the determination of its positioning shall be performed with the rolling sphere method described in IEC 62305-3. The following clauses give some procedures for the installation of the LPS. 6.1.1 Metallic tower The LPS rod(s

42、) shall be connected directly to the structure of the metallic tower. Therefore, the structure of the metallic tower will conduct the stroke current to ground and there is no need to install lightning down conductors. NOTE If the total cross-section of the tower structure is less than 125 mm2, then

43、the tower shall be treated as a non-metallic tower, as described in clause 6.1.2. 6.1.2 Non-metallic tower If the structure that supports the antennas is not metallic (e.g., wood pole) or if it is metallic but its cross-section is less than 125 mm2, it is necessary to install two down-conductors to

44、earth the LPS rod(s). The down conductors shall not be insulated from the tower and they shall have a minimum cross-section of 50 mm2 each. The down conductors shall be installed on opposite sides of the tower. 6.1.3 Building In the majority of the cases, the nearby tower will protect the building a

45、gainst direct strikes. However, the need for an LPS in the building shall be investigated with the rolling sphere method described in IEC 62305-3. If the building requires an LPS, it shall be earthed in the earthing system of the RBS, which is described in clause 6.3. 4 Rec. ITU-T K.56 (2010)/Cor.1

46、(07/2017) Figure 1 General view of earthing and bonding procedures in the external area 6.2 Bonding in the tower 6.2.1 Feeder cables The wave-guide and the external conductor of coaxial cables, henceforth referred as feeder cables, shall be bonded to the metallic tower (or to the feeder tray) near t

47、he antenna, as shown in Figure 1. A weatherproof connector shall make the connection to the feeder cable in order to avoid corrosion, and the connection to the tower (or feeder tray) structure shall also be protected to avoid ingression of moisture. Usually, the cable manufacturers provide appropria

48、ted earthing kits for these connections. The earthing kits shall have a connector to be attached on the bare outer surface of the feeder (the feeder plastic outer jacket shall be removed), another connector to be attached to the tower structure (paint shall be removed) and a conductor bonding the tw

49、o connectors. The earthing kit shall also contain protective coatings to be applied on the connections. Figure 2 shows schematically the installation of an earthing kit before the application of the protective coating. NOTE 1 For non-metallic towers or metallic towers with a cross-section smaller than 125 mm2, the bonding shall be made to the lightning down conductor. NOTE 2 Some types of antenna are inherently connected to the tower by design. In this ca