FIELD: automatic control facilities for ring lines fed from double-transformer substations. SUBSTANCE: known method involves recording of inrush short-circuit current, measurement of time intervals between first and second inrush currents, measurement of second inrush short-circuit current, and data acquisition by magnitude of and time interval between inrush currents. Novelty is that time is measured since moment of first inrush short-circuit current at transformer buses of main power supply equal to operation delay time of mains automatic backup control, buses of standby power supply are checked for second inrush short-circuit current as soon as mentioned measurement is ceased, and if this current occurs, fact of automatic backup control failure to operate in response to short circuit is stated. Known method does not yield information about operation of automatic backup control center (its failure to respond to short circuit). Proposed method makes it possible to acquire information about failure of automatic backup control to respond to steady short circuits in ring line fed from buses of double-transformer substation. EFFECT: enlarged functional capabilities. 2 dwg
