Safety aspects of GSM systems on high voltage towers

Low voltage applications mounted on high voltage towers may pose a safety problem in the low voltage network when a flashover occurs over the high-voltage insulators. To study the effects experimentally, a 150 kV system was made available. On a high voltage tower carrying a cellular phone base station, one phase insulator was shorted to the tower. A current of about 200 A was injected into that phase at a large distance. The authors measured the current distribution and the relevant voltages in the low voltage network. A experimental data agree with EMTP calculations. Appropriate measures to guarantee safety for persons and electronic equipment are discussed.