CHARACTERISTICS OF EARTH FAULTS IN ELECTRICAL DISTRIBUTION NETWORKS WITH HIGH IMPEDANCE EARTHING

This paper presents an analysis and comparison of earth fault characte ristics in the medium voltage distribution networks (20 kV) with high impedance earthing. The results presented are based on the evaluation of 476 real case data recordings, obtained from substations of distrib ution networks with an unearthed or a compensated neutral during the o bservation period of 3 years, 1994-1996. The networks were mainly of o verhead construction, with a smaller share of underground cables. In t he occurrence of disturbances, the traces of phase currents and voltag es and neutral currents and voltages were recorded at two feeders at t wo substations. The study dealt with the clearing of earth faults, rel ation between short circuits and earth faults? are extinction, arcing fault characteristics, appearance of transients and magnitudes of faul t resistances. The results contribute to various developments of distr ibution automation and protection systems. (C) 1998 Elsevier Science S .A. All rights reserved.