METHOD OF SELECTIVE PROTECTION FROM EARTH-FAULTS IN ELECTRICAL NETWORK WITH SMALL EARTH-FAULT CURRENTS

摘要

FIELD: electricity.;SUBSTANCE: invention is used in electrical engineering. According to the method the zero-sequence currents of all outgoing connections are measured, the connection currents exceeding a minimum established level are selected, the phase shifts of zero-sequence currents of all outgoing connections with reference to the base signal are determined, the signal with minimum phase shift with reference to the base signal is determined, the decision is made regarding the feeder, where the current has minimum phase shift, is damaged, meanwhile the instantaneous values of zero-sequence currents of all connections are summarised, and the base signal is formed on the basis of this sum. In case of presence in the network of earthing inductor, resistor or their combination, the current in the grounding circuit is measured, and this current in the grounding circuit, is accepted as a base signal.;EFFECT: reliability improvement.;2 cl, 3 dwg