Ground Resistance-Revisited

The nature of ground resistance is examined to explain the high impedance of faults directly to ground as contrasted to conventionally assumed low impedance ground faults to neutral conductor or to towers with low footing resistance. High impedance faults are shown to be inherently nonlinear due to the characteristics of soil. This nonlinearity is shown to be different from that of the arcing between conductor and ground. The harmonic content of the resulting current is judged to have characteristics which can be used to distinguish such faults from normal load variations.