METHOD FOR DETERMINATION OF DISTANCE TO LOCATION OF ONE-PHASE SHORT CIRCUIT TO EARTH OR DEFECT OF INSULATION IN ELECTRIC NETWORKS WITH INSULATED AND COMPENSATED NEUTRAL

摘要

Method for determination of distance to location of one-phase short circuit on earth or defect of insulation in electric networks with insulated and compensated neutral relates to electrical engineering and can be used for microprocessor relay protection of cable lines. The method includes measurement of instantaneous values of currents and voltages of emergency state and use of known linear parameters of line. The method differs with fact that by instantaneous values of currents and voltages through digital filtration one registers effective values of first harmonic of current and voltage of damaged phase of line with respect to earth, with registration of electric angles between respective value and first harmonic of short circuit current of zero sequence, and after that one determines distance to place of failure by means of calculation by respective formula. The method provides decrease of error of determination of needed values, this increases accuracy of determination of distance to location of damage in cable.