Safety Analysis at Overhead Line Towers in Close Proximity to the Substation

This paper proposes a mathematical model for the analysis of safety conditions at a transmission-line tower located in close proximity to the substation, of which the line is connected to, arising in the case of a single-phase-to-ground fault at the tower. The model takes into account the mutual interaction of the substation and tower ground electrodes affecting the currents discharging from these electrodes into the surrounding soil and the potential distribution on the ground surface. A practical, quite general case of a double-circuit line having two ground wires of different types is considered. It was shown that the negligence of the mutual effects of the two ground electrodes might lead to very erroneous conclusions regarding the maximum touch-and-step voltages appearing at the tower location in the fault case, implying unnecessary extra cost and labor to meet the safety standards.