Computer-aided calculations of earth potential rise in high voltage overhead lines

High voltage overhead power lines with earth wires comprise towers made of conductive material. Some towers are in locations where people can be expected to be either for a long time or for a short time but very frequently. Evaluation of shock hazard near such towers requires calculation of line-to-earth short-circuit current, earth current and especially earth potential rise. Number of towers in high voltage power lines can exceed 100. Thus, evaluation of effectiveness of protection against electric shock is time-consuming, so computer software for fast calculation of earth potential rise can be useful. This paper presents a method of computerized calculation of earth potential rise and earth current distribution in overhead lines with earth wires. The example results of calculations are presented for two selected cases of transmission system.