DEVELOPMENT OF AN INTEGRATED METHOD FOR DETERMINING SINGLE-PHASE EARTH FAULT CURRENTS IN THE CAREER DISTRIBUTION NETWORK

The paper discusses methods for determining single-phase ground fault currents in the quarry's electrical distribution network. The appearance of these short circuits in an electrical network with an isolated or compensated neutral leads to the appearance of significant overvoltages of undamaged phases at the time of the circuit and a decrease in the stability of the functioning of protection devices against single-phase ground faults. It has been established that oscillography is carried out to study the components of higher harmonics in the ground fault current, the network voltage, the neutral bias voltage, as well as to determine the time required to restore the voltage on the grounded phase to a normal value after disconnecting the ground fault. Methods for determining the current of single-phase earth faults by indirect methods are presented, corresponding measurement schemes are presented in the absence of natural unbalance voltage, without a voltage transformer, as well as at a certain value of natural unbalance voltage. The methods presented in the work for calculating single-phase ground fault currents in the quarry distribution network make it possible to give substantiated practical recommendations for improving the operation of ground fault protection and current short circuit protection. In the course of conducting comprehensive studies of single-phase earth fault currents, oscillograms of transient, steady-state single-phase earth faults, and transient process of disconnecting the fault were obtained, which made it possible to optimize the parameters of the electrical network of the quarry in question.