Statistical Characteristics for Parameters of Transient Processes at Arcing Ground Faults in Cable Networks

The paper presents the results of complex analysis of amplitude, velocity and time parameters for currents and voltages at arcing ground fault in power cable. The analysis is based on random samples obtained from real oscillograms. These oscillograms are recorded during experimental investigations in the 6 kV network. Hypotheses of distribution laws, outliers detection and correlational relationship are tested. Regression statistics is obtained for the following main parameters of arcing ground fault in cable insulation: duration of single breakdowns, duration of no-current condition, overvoltage level, rate of high-frequency arc current change before quenching, voltage recovery rate for a faulted phase under no-current condition, neutral-to-ground voltage amplitude after breakdown, breakdown voltage for a faulted phase. Obtained statistical characteristics for arcing breakdown parameters and stochastic relationships between them can be used for further development of mathematical models of arcing in power cable insulation and for checking of relay protection efficiency using physical models.