Case study # 2.8 Title Earth wire voltage drop in telecommunication centre Type of trouble Damage. Source of trouble Lightning. System affected Transmission equipment. Location Telecommunication centre. Keywords Damage, lightning surge. Version date 2004-01-01 System configuration During thunderstorms, several line cards of a multiplex, located in a radio station, were frequently damaged. Located on the top of a mountain, the radio station is composed of a 40-m high telecommunication tower and an adjacent 2-floor building (Figure 2.8-1). The antennas on the tower are connected to the radio equipment inside the building by wave-guide cables. In the building, on the ground floor, there are the entrance of the low voltage power line through an insulation transformer, the power station, and the main earth terminal of the building. On the first floor, there is the radio equipment. On the second floor, there are radio equipment and a multiplex. The latter serves customers located close to the radio station. The customers are connected to the multiplex by 30 pairs of 9/10 cable. This cable can be defined as a \"lightning cable\", i.e., the cable can resist high values of direct lightning current. Though it has been installed a long time, lightning never damaged the cable. MDF GDTs Radio equipment Earth wire voltage drop Wave-guide Power lines cable Power station Telecom cable Miti(08)_F2.8-1 Figure 2.8-1 – Radio station Copyright © ITU 2010 – All Rights Reserved