FIELD: power engineering. SUBSTANCE: transformer 2 used for superhigh-current protection of insulated-neutral lines during ferroresonant processes has its two primary windings connected across line voltages through substation buses. Capacitive voltage divider 3 is connected to phase lead of buses 1 common for two primary windings of transformer 2 and ground; output of capacitive divider 3 is connected together with transformer secondary leads to line voltage changer 4 whose outputs are connected to inputs of secondary voltage circuits to ensure monitoring of all supply voltages and zero-sequence voltage. EFFECT: improved reliability and resistance to alternating arcing ground faults of supply mains. 1 dwg
