Soil Effects on Ground Fault Currents

A detailed parametric analysis shows that soil characteristics have considerable effect on ground-fault currents and the resulting induced potentials, whether caused by electromagnetic or resistive (direct earth connection) coupling. The computer results presented in this study, are based on a theoretical method developed by the first author [1]. This method is sufficiently general to simultaneously consider all the significant variables, such as self and mutual impedances of overhead and underground conductors, substation ground impedances and transmission line tower resistances. The results, which complement the theoretical method described in [1], are presented in several graphs which can be used as a design guide. Satisfactory agreement is obtained between measured and computed results.