Case study # 2.1 Title Lightning surge troubles on transmission equipment, TCM, and MUX Type of trouble Damage. Source of trouble Lightning surge. System affected Transmission equipment and MUX. Location Telecommunication centre. Keywords Damage, lightning surge. Version date 2004-01-01 System configuration The system configuration for a lightning surge trouble case is shown in Figure 2.1-1. As depicted in the figure, a transmission equipment, a TCM (transmission communication module), was located in the telecommunication centre, and there was a building with an antenna tower next to the telecommunication centre. Coaxial cables were used between the two buildings to connect the transmission equipment with the radio equipment. The earthing of the telecommunication centre and the earthing of the building were not connected to each other. The main distribution frame (MDF) earthing was not connected to the telecommunication centre earthing, either. Lightning Radio tower Telecommunication centre MDF MDF TCM PDF RF SR4 SR4 MDF earthing bar 200 V a.c. IF A Coaxial cable MUX Miti(08)_F2.1-1 MDF earthing Telecom earthing MDF earthing Figure 2.1-1 – System configuration Measurement/Searching techniques/Experiment As a result of the investigation, lightning surge strikes were detected at the radio antenna tower by visual inspection. Lightning surge current flowed through the tower, the earthing, power supply, MUX and TCM. It was considered that the surge current in the coaxial cables could damage the telecom equipment, TCM and MUX. Copyright © ITU 2010 – All Rights Reserved