Analysis of Transmission Tower Potentials During Ground Faults

Since ground fault currents in high-voltage systems are on the increase, the hazards associated with transmission tower voltages during ground faults have become of concern. An analytical method is presented to determine these voltages for long and short lines, arbitrary ground network terminations, and any combination of skywires and counterpoise conductors. The proportion in which the fault current is supplied by the line on both sides of the fault location is taken into account, and the effect of fault currents flowing in parallel external circuits is also considered. The touch and step potentials at the faulted tower are determined and an assessment is given of the hazard they may represent. In a numerical example, several measures aimed at reducing this hazard are compared.