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.120 TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (12/2016) SERIES K: PROTECTION AGAINST INTERFERENCE Lightning protection and earthing of a miniature base station Recommendation ITU-T K.120 Rec. ITU-T K.120 (12/2016) i
2、 Recommendation ITU-T K.120 Lightning protection and earthing of a miniature base station Summary Recommendation ITU-T K.120 provides guidelines for lightning protection and earthing of miniature base stations. A miniature base station is a new type of radio base station, which is different from a d
3、istribution base station (DBS) in many respects. The change of installation environment is the critical factor to affect the lightning protection of miniature base stations. Miniature base stations have low radio frequency (RF) power and a small volume in size, which makes them suitable for the cove
4、rage of hotspots and/or blind areas for improving communication quality. Miniature base stations are ordinarily installed in residential or densely populated urban areas (unconventional telecommunication site), for example, ceiling (indoor), external wall, advertising board, rooftop, street light, l
5、ow-voltage power pole, and so on, where the installation, wiring and earthing is difficult. In comparison, distribution base stations, within the domain of macro-base stations, have high RF power and a large volume in size, which is suitable for wide area coverage. Usually a DBS is installed in a co
6、nventional telecommunication environment, where the installation, wiring and earthing is easier. Though some installation scenarios are covered by Recommendation ITU-T K.97, lightning protection of miniature base stations are not fully specified in the ITU-T K series of Recommendations. The purpose
7、of this Recommendation is to give guidance on the protection of miniature base stations against lightning surge, especially for those which are in unexposed environments (to lightning) and unconventional telecommunication sites. Protection of miniature base stations is achieved by either surge prote
8、ctive devices and/or components or isolation of interfaces. For those where earthing is not available or it is difficult, the base station can be unearthed (floating), as long as the safety measures against electric shock are considered adequately. Bonding configurations of the protection module and
9、 of the optical fibre cable are also illustrated. History Edition Recommendation Approval Study Group Unique ID* 1.0 ITU-T K.120 2016-12-14 5 11.1002/1000/13136 Keywords Lightning, miniature base station, surge, unconventional telecommunication site, unexposed environment (to lightning), * To access
10、 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.120 (12/2016) FOREWORD The International Telecommunication Union (ITU) is the United
11、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 tariff questions and issuing Recommendati
12、ons 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 Recommendations on these topics. The approva
13、l 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 Recommendation, the expression “Administration
14、“ 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., interoperability or applicability) and compliance
15、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 compliance with the Recommendation is requ
16、ired 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, validity or applicability of claimed Intellect
17、ual 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 required to implement this Recommendation. How
18、ever, 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 reproduced, by any means whatsoever, without the p
19、rior written permission of ITU. Rec. ITU-T K.120 (12/2016) iii Table of Contents Page 1 Scope . 1 2 References . 1 3 Definitions 2 3.1 Terms defined elsewhere 2 3.2 Terms defined in this Recommendation . 2 4 Abbreviations and acronyms 2 5 Conventions 3 6 Reference configuration 3 6.1 Typical configu
20、ration of miniature base systems . 3 6.2 The ports susceptible to lightning surges . 3 7 Need for protection . 4 8 Lightning protection . 5 8.1 Air-termination system and down conductor . 5 8.2 Earth electrode 6 8.3 Protection of power port . 6 8.4 Protection of signal port . 7 9 Bonding configurati
21、on 8 9.1 The power distribution . 8 9.2 Bonding of equipment 8 9.3 Bonding of shielded cable 9 9.4 Bonding of optical fibre cable 9 9.5 Other metallic parts 9 10 Miscellaneous . 9 Appendix I Examples of earthing means for an MBS installed in two typical scenarios . 10 I.1 Scenario I: MBS installed o
22、n external wall 10 I.2 Scenario 2: MBS installed on a street light 11 Bibliography. 14 Rec. ITU-T K.120 (12/2016) 1 Recommendation ITU-T K.120 Lightning protection and earthing of a miniature base station 1 Scope This Recommendation addresses the lightning protection, earthing, bonding and safety co
23、nsiderations for miniature base stations. The purpose of this Recommendation is to give guidance on the protection of miniature base stations against lightning surge, especially those which are in unexposed environments (to lightning) and unconventional telecommunication sites. For miniature wireles
24、s stations installed in conventional telecommunication sites or highly exposed environments (to lightning), ITU-T K.97 is applicable. 2 References The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommen
25、dation. 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 reference
26、s 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.21 Recommendation ITU-T K.21 (2016), Resistibility of telecommunicat
27、ion equipment installed in customer premises to overvoltages and overcurrents. ITU-T K.27 Recommendation ITU-T K.27 (2015), Bonding configurations and earthing inside a telecommunication building. ITU-T K.45 Recommendation ITU-T K.45 (2016), Resistibility of telecommunication equipment installed in
28、the access and trunk networks to overvoltages and overcurrents. ITU-T K.56 Recommendation ITU-T K.56 (2010), Protection of radio base stations against lightning discharges. ITU-T K.71 Recommendation ITU-T K.71 (2007), Protection of customer antenna installations. ITU-T K.97 Recommendation ITU-T K.97
29、 (2014), Lightning protection of distributed base stations. ITU-T K.109 Recommendation ITU-T K.109 (2015), Installation of telecommunication equipment on utility poles. ITU-T K.112 Recommendation ITU-T K.112 (2015), Lightning protection, earthing and bonding: Practical procedures for radio base stat
30、ions. IEC 61643-11 IEC 61643-11 (2011), Low-voltage surge protective devices Part 11: Surge protective devices connected to low-voltage power systems Requirements and test methods. IEC 62305-1 IEC 62305-1 (2010), Protection against lightning Part 1: General principles. IEC 62305-2 IEC 62305-2 (2010)
31、, Protection against lightning Part 2: Risk management. 2 Rec. ITU-T K.120 (12/2016) IEC 62305-3 IEC 62305-3 (2010), Protection against lightning Part 3: Physical damage to structures and life hazard. IEC 62305-4 IEC 62305-4 (2010), Protection against lightning Part 4: Electric and electronic system
32、s within structures. 3 Definitions 3.1 Terms defined elsewhere This Recommendation uses the following terms defined elsewhere: In this Recommendation, definitions already introduced by ITU-T K.56, ITU-T K.97 and ITU-T K.112 are used to maintain conformity. Definitions in ITU-T K.27, related to bondi
33、ng configurations and earthing, also apply. 3.2 Terms defined in this Recommendation This Recommendation defines the following terms: 3.2.1 miniature base station: A type of radio base station (RBS) whose size and RF power are much smaller or lower than typical macro-base stations or DBS base statio
34、ns. 3.2.2 conventional telecommunication site: A typical telecommunication site (including remote electronic sites), where the lightning protection, earthing and bonding configurations are compliant with the requirements of the relevant ITU-T K series of Recommendations, e.g., ITU-T K.27 and ITU-T K
35、.35. 3.2.3 unconventional telecommunication site: Using the simple facilities, such as street lighting poles, urban and rural transportation poles, advertising boards, etc., for the installation of telecommunication equipment, where lightning protection, earthing and bonding configurations are not c
36、ompliant with the requirements of the relevant ITU-T K series of Recommendations, e.g., ITU-T K.27 and ITU-T K.35. 4 Abbreviations and acronyms This Recommendation uses the following abbreviations and acronyms: BBU Base Band Unit CBN Common Bonding Network DBS Distribution Base Station EUT Equipment
37、 Under Test GPS Global Positioning System ICT Information Communication Technology LPZ Lightning Protection Zone MBS Miniature Base Station PE Protective Earthing conductor PoE Power over Ethernet PSE Power Sourcing Equipment RBS Radio Base Station RCD Residual Current Operated Device Rec. ITU-T K.1
38、20 (12/2016) 3 RF Radio Frequency RRU Remote Radio Unit SPD Surge Protective Device 5 Conventions None. 6 Reference configuration 6.1 Typical configuration of miniature base systems A miniature base system typically consists of a miniature base station, antenna, power supply unit and transmission eq
39、uipment. In some cases, the antenna and/or transmission unit is/are integrated into the base station. A typical configuration of a miniature wireless base system is as follows. Figure 1 Typical configuration of miniature wireless base system A miniature base station has low RF power and a small volu
40、me in size, which makes it suitable for the coverage of hotspot areas and blind areas for improving communication quality. A miniature base station is ordinarily installed in residential or densely populated urban areas (unconventional telecommunication site), for example, ceiling (indoor), external
41、 wall, advertising board, rooftop, street lamp, power utility pole, and so on, where the installation, wiring and earthing is difficult. In comparison, a distribution base station, within the domain of macro-base stations, has high RF power and a large volume in size, which is suitable for wide area
42、 coverage. Usually a DBS is installed in a conventional telecommunication environment, where the installation, wiring and earthing is relatively easy. Besides, some miniature base stations take advantage of existing RBS sites, including DBS sites, which are considered as conventional telecommunicati
43、on environments. In these cases, the requirements of ITU-T K.56, ITU-T K.97 and ITU-T K.112 apply. 6.2 The ports susceptible to lightning surges There are four types of ports that are susceptible to lightning surges; these are shown in Figure 2. Power port: Either alternate current (AC) or direct cu
44、rrent (DC). In some cases, the station is powered by PoE, which is classified as a signal port. 4 Rec. ITU-T K.120 (12/2016) Signal or control port: e.g. transmission port (including PoE), monitoring port and control port. RF port: all kinds of RF ports, such as antenna, GPS, etc. Earthing port: the
45、 earthing port of equipment. Figure 2 The ports susceptible to lightning surge 7 Need for protection The main key factors to be considered when determining the need for protection, and any necessary protective measures to be taken, are as follows: the geographical environment where a miniature base
46、station is installed, e.g., urban environment, suburban environment or rural environment, as defined in IEC 62305-2; the lightning ground flash density, or roughly the keraunic level; the lightning protection zone (LPZ); the type of power supply, the length of power cable and its exposure to lightni
47、ng strikes. the type of signal transmission, the length of signal cable and its exposure to the lightning strikes. Subsequently, the installation scenarios of miniature base stations can be classified as follows: Unexposed environment: It can be considered as an unexposed environment if a miniature
48、base station is installed indoors or on the lower building external wall, and powered through an indoor distribution box or panel. In this environment, the surge current is limited by current sharing and by isolating interfaces and/or SPDs upstream. The lightning electromagnetic field may be attenua
49、ted too. Low-exposed environment: It can be considered as a low-exposed environment if a miniature base station is installed on the upper building external wall, street lamp, advertising board, power utility pole, urban ordinary building rooftop, and in regions of low lightning activity. In this environment, direct lightning current is not likely to be injected into the system, but inductive lightning current can be produced to some extent. Medium-exposed environment: It can be c
