Time domain analysis of the lightning current distribution at the HV tower with GSM system

GSM base stations are often placed in the poles of power transmission lines. Such base stations are usually powered from the low-voltage network through an isolating transformer to separate the high- and low-voltage networks. The isolating transformer serves to ensure security at other customers´ premises especially in case of lightning stroke at the line, which is a frequent cause of flashover of the high-voltage insulators and a subsequent phase to ground fault. To optimize such protection better knowledge of the currents and voltages in the early time of the lightning stroke is required. This paper presents simulation results for the lightning current distribution between the earth wires, grounding systems and power cable network. The analysis is applied to a practical case.