Oscillography of transient processes at physical phase-to-ground fault modeling in operational 6-35 kV networks

The paper presents methods of accurate determination of single phase-to-ground currents, advantages and disadvantages of these methods, and general requirements to the measuring equipment used in oscillography of transient processes at single phase-to-ground faults. These methods have been tried in operational 6-35 kV networks for 8 years. Experimental investigations allow doing research of main parameters of a zero-sequence circuit. Using recorded oscillograms, we can analyze the character of transient processes, evaluate the efficiency of the compensation system, suppose the nature of processes, and determine overvoltage levels. Based on experimental investigations and calculations, recommendations on effective internal overvoltage protection at arcing ground faults can be proposed.