New improved method for measuring the earthfault-distance in non-solid grounded networks

Current earth fault distance measurement based on symmetrical components does not work very well in compensated systems because the steady-state currents through the fault location are significantly smaller than the load currents. It is not possible to distinguish between load current and fault current. It has also been assumed that the fault impedance, including the arc, is a linear impedance. However, this is not the case in the real world, especially for faults in the cable section of a line. The air gap creates an additional layer of insulation with increased and variable ignition voltage. This non-linearity affects the current waveform, voltage waveform, and frequency of the low-current arc. With the new modified method, it is now possible to distinguish between the fault current and the load current and to compensate for the effects of the nonlinearities of the fault impedances. The accuracy of the impedance measurement from the measuring point to the fault location is significantly improved. This paper presents the new method in detail for self-extinguishing and re-igniting earth faults in overhead and cable networks.