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Cotonou, Benin, 19 July 2012 Relevant ITU-T Recommendations for the Protection of Base Stations Ahmed ZEDDAM Ahmed ZEDDAM, ITU-T SG5 Chair France Telecom.

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Presentation on theme: "Cotonou, Benin, 19 July 2012 Relevant ITU-T Recommendations for the Protection of Base Stations Ahmed ZEDDAM Ahmed ZEDDAM, ITU-T SG5 Chair France Telecom."— Presentation transcript:

1 Cotonou, Benin, 19 July 2012 Relevant ITU-T Recommendations for the Protection of Base Stations Ahmed ZEDDAM Ahmed ZEDDAM, ITU-T SG5 Chair France Telecom Orange ITU Workshop on Tackling climate change and Specific Absorption Rate (SAR) Measurement (Cotonou, Benin, 19 July 2012)

2 Cotonou, Benin, 19 July INTRODUCTION LIGHTNING PROTECTION RECOMMENDATION ITU-T K.56 Need of Protection Earthing and Bonding procedures Use of SPDs DECOUPLING WITH POWER NETWORK CONCLUSION Outline

3 3 Cotonou, Benin, 19 July 2012 Introduction Protection of an installation may require a combination of: Lightning protection for the building Protection on incoming lines Resistibility of equipment Earthing and bonding of installation This presentation is about the protection of equipment within a base station

4 4 Cotonou, Benin, 19 July 2012 SG 5 role in equipment protection SG 5 is unique SDO in overvoltage protection Ensures coordination of the equipment and external protection Considers installation practices and their effect on resistibility requirements

5 5 Cotonou, Benin, 19 July 2012 Resistibility and protection Preventing equipment damage may require a combination of resistibility and protection Resistibility is The ability of the equipment to withstand an overvoltage or overcurrent Protection is The addition of primary protection to prevent damage from larger surges Need to check that the protector operates and protects the equipment

6 6 Cotonou, Benin, 19 July 2012 Lightning discharges can reach a telecommunication system by the following mechanisms: Lightning Protection

7 7 Cotonou, Benin, 19 July 2012 Direct strikes Lightning Protection

8 8 Cotonou, Benin, 19 July 2012 Coupling through the earth Lightning Protection

9 9 Cotonou, Benin, 19 July 2012 Coupling through electromagnetic fields Lightning Protection

10 10 Cotonou, Benin, 19 July 2012 If adequate protection is missing, the lightning surges can be very dangerous to telecommunications systems, threatening : Terminal equipment Station equipment And even human beings In order to protect the telecommunications systems against the effects of lightning discharges, the ITU-T SG-5 produced Handbooks and a set of Series K Recommendations: Lightning Protection

11 Recommendation ITU-T K.56 : Protection of radio base stations against lightning discharges Presents the techniques applied to a telecom. radio base station in order to protect it against lightning discharges The need of protection is obtained from the methodology contained in IEC , 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), bonding 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 applied to cable trays and equipment frames Cotonou, Benin, 19 July

12 Need of protection The risk assessment of the RBS shall be performed according to [IEC ] in order to determine a Lightning Protection Level (LPL) for the design of the protection procedures. Table 1 shows some lightning flash parameters associated with each LPL. Cotonou, Benin, July ParameterUnit LPL IIIIIIIV Maximum peak currentkA Maximum current rate of rise kA/ s Radius of electro-geometric spherem Probability of flash% Table 1 – Lightning flash parameters from [IEC ]

13 Earthing and bonding procedures applied to the external area Cotonou, Benin, July Figure 1 – General view of earthing and bonding procedures in the external area

14 Earthing configuration Cotonou, Benin, July Figure 5 – Earthing system of the RBS

15 Earthing configuration A bare conductor forms a ring electrode around the building and another ring around the tower. Multiple earthing conductors are used to interconnect the two rings (three, in the figure). The distance of the buried conductor from the associated structure shall be approximately 1.0 m, and the depth of the conductor shall be at least 0.5 m. Vertical rods should be installed along the ring electrode, as shown in Figures 1 and 5. These rods should be made of steel covered with copper or made of galvanized steel, and they shall be attached to the earth electrode by appropriate connectors. The legs of a metallic tower (or the down conductors of a non-metallic tower) shall be bonded through short connections to the tower's earthing ring. The steel reinforcement of the tower's basement, if any, shall also be connected to the earthing ring (see Figures 1 and 5). The steel reinforcement of the building's structure shall be bonded to the earthing ring at least at its four corners. If the building is metallic, its feet shall be bonded to the earthing ring. The earthing ring of the building shall be connected to the main earthing bar (MEB) located inside the building, preferably on the wall that faces the tower. The earthing conductor shall be as short as possible and have 50 mm 2 as the minimum cross-section area. All conductors in contact with the earth should be made of copper or steel covered with copper and have 50 mm 2 as the minimum cross-section area. Galvanized steel conductors could also be used, with 90 mm 2 as the minimum cross-section area. A fence usually surrounds the terrain where the RBS is located. If the fence is metallic, some precautions have to be taken in order to minimize the hazard due to the voltages transferred by the fence. Cotonou, Benin, July

16 Bonding at the feed-through window Cotonou, Benin, July Figure 6 – Example of earthing the feeder cable at the feed-through window

17 Use of SPDs Cotonou, Benin, July Figure 7 – Diagram of the electric board

18 Installation of SPD in the electric board Cotonou, Benin, July Figure 8 – Scheme for SPD installation on TT power systems The SPDs shall comply with [IEC ] The SPD installed in the electric board shall coordinate with the SPD installed in the power meter station [see IEC for coordination] Annex A of [ITU-T K.66] gives information on SPD installation for different power systems.

19 Protection of telecommunication lines Cotonou, Benin, July The procedures for the protection of telecommunication lines against direct and indirect lightning discharges can be found in [ITU-T K.47] and [ITU-T K.46], respectively, taking into account [ITU-T K.72]. Figure 11 – Installation of SPD in the distribution frame

20 Example of earthing and bonding configuration inside an RBS Cotonou, Benin, July More information on the implementation of earthing and bonding configurations can be found in [ITU-T K.27] and [ITU T K.35

21 Decoupling with power network Cotonou, Benin, July D1 : Distance entre la prise de terre des masses du poste de transformation HTA/BT et la prise de terre du Neutre BT, D2 : La distance entre a prise de terre des masses du poste de transformation HTA/BT et la prise de terre du Site de Radiocommunication, D3 : Distance entre a prise de terre du Neutre BT et la prise de terre du Site Radiocommunication

22 Decoupling with power network Cotonou, Benin, July

23 CONCLUSION Protection of Base Stations is based on the combination of : Lightning protection Lightning protection for the building SPDs Protection on incoming lines (SPDs) Resistibility Resistibility of equipment Earthing and bonding Earthing and bonding of installation Decoupling Decoupling with power network ITU-T K.56 Recommendation ITU-T K.56 provides useful information for the protection of RBS and refers to other relevant Recommendations Cotonou, Benin, July

24 Cotonou, Benin, 19 July Thank you


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