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 conductors 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 used to distinguish such faults from normal load variations. Specifically, the magnitudes of the resulting harmonic currents appear sufficiently predictable to be utilized in a high-impedance fault detector.< >