FIELD: electricity.
SUBSTANCE: use: in electric power engineering. According to the method, transient phase voltages on the buses of the power centre are recorded and by means of their processing the fact of arc short circuit to ground is established, as well as the damaged phase by the highest phase voltage derivative at phase breakdown moment of breakdown; in the voltage derivative over the damaged phase dud/dt find its maximum at the moment of breakdown of the insulation and calculating pre-breakdown time relative to the previous breakdown Δtpre = tm1 - tm0, which should exceed 1 ms, if this condition is not satisfied, then such closure (phase failure breakdown) processing is not performed; when condition Δtpre > 1 ms are used to determine polarity of mean pre-breakdown voltage on the damaged phase and average currents of zero sequence in all feeders extending from busbars; for this from time of maximum of derivative tm1 are backed to beginning of oscillogram of voltage on damaged phase for time ΔtU≅(0.025...0.1)∙T0 (T0 is the industrial frequency period), during which average mean pre-breakdown voltage Up.av. is calculated; from moment of maximum derivative voltage on damaged phase tm1 for time equal to one third of period of free charge exchange oscillations of electric network ΔtI, determining zero-sequence average currents in all outgoing feeders, leaving two with maximum modulus values; polarities of these two zero sequence sign(I0av.) are compared with polarity of average pre-breakdown voltage on the damaged phase sign(Up.av.), one of two allocated feeders, in which polarity of average current of zero sequence coincides with polarity of average pre-breakdown voltage on damaged phase, that is performed condition sign(Up.av.)=sign(I0av.), is the feeder with single-phase ground fault.
EFFECT: technical result is increase in reliability and veracity of determination of feeder with single-phase unstable arc closure to earth in electric networks with inefficient earthed neutral.
1 cl, 2 dwg, 1 tbl
