FIELD: electrical engineering. SUBSTANCE: device has unit which checks phase voltage. Its output is connected to three intermediate relays which power contacts are connected to power supply circuit of electric motor and phase-shifting unit. device has filter of reverse sequence voltage which checks symmetry of voltage at output of phase shifting unit. Said unit which checks phase voltage is designed as three voltage comparators which non-inverting inputs are connected to mains phases through diodes and resistive voltage dividers. Their joined inverting inputs are connected through diodes to reference voltage source, setter of minimal mains voltage, unit which checks reverse sequence voltage. Outputs of voltage comparators are connected to actuating members which have three single-junction transistor amplifiers which circuits comprise three actuating relays. EFFECT: increased functional reliability of electric drive. 1 dwg
