Elimination of the intermittent earth faults

Abstract

In the paper, the subject of the intermittent earth faults and their detection has been discussed. The intermittent faults belong to a group of hardly detectable ones due to the low and unstable measuring signals. The analysis has been carried out for typical medium voltage distribution network under faults with different characteristics. It was shown that the criterion magnitudes used up to now in the to-ground protections can be ineffective here. Influence of various methods of the measuring signals filtration (Morlet wavelet filter, averaging filter) on the criterion values of protections has been assessed. An original algorithm with logic inertia improving the effectiveness of the to- ground protection under intermittent fault conditions has been proposed.