Earth fault analysis using measured data from fault experiments in actual distribution network

This paper presents the results of the analysis of a vast fault records database. The fault records were obtained during numerous experiments performed from 2005 to 2011 in real resonant-earthed distribution networks. The purpose of these experiments was to provide data either for verifying distribution network safety during earth faults or for testing methods of earth fault location or elimination. This is why the measurements were performed during earth faults at various points in the network and for various operating conditions concerning the size of the network, the off-resonant degree (undercompensation, overcompensation and full compensation) and the fault resistance (including arc earth faults) and the network load. Some results of these experiments have been already published — [1], [2]. A detailed analysis of the obtained measurement records having been completed, its results could be evaluated with respect to the dimensioning of network components, ground fault protection setting and particularly as a base for a further development of the earth fault location methods. A significant contribution of the paper is the evaluation of the measurements of earth faults in extra-large compensated distribution networks (with a capacitive current up to 800 A), not commonly operated at present, the appearance of which can be — taking into account distribution network development — expected in the future.