FIELD: electricity.
SUBSTANCE: use of the invention: in electrical engineering. The technical result consists in the enlargement of functional capabilities of the method. According to the method, from the moment of disappearance of one or all line voltages and absence of the short-circuit (SC) current at the transformer input, counting of the total time is started, which is equal to the delay time of a protection actuation and the delay time of automatic reclosing of the main switch (MS); at the end of counting of the total time the sounding pulses are sent to all wires of this line, the time is measured, during which they achieve reflection points; the distance to these points is calculated and they are compared to each other and to the distance to the MS installation place, and if the two calculated distances are equal to each other and less than the third one, which is equal to the distance to MS, then, a conclusion is made on the stable two-phase SC. If all the calculated distances are equal to each other and less than the distance to MS, then, a conclusion is made on the stable three-phase SC and a signal is supplied to prohibit automatic reclosing of the main switch of the line feeding the transformer substation.
EFFECT: proposed method allows performing prohibition of automatic reclosing of the main switch of a line feeding the transformer substation with the determination of the type of the short circuit.
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