FIELD: electrical engineering; three-phase motor control.
SUBSTANCE: device designed to disconnect three-phase motor from supply mains upon occurrence of phase failure has three-phase optoelectronic relay and three-phase motor that functions as load; in addition it is provided with unit designed to protect motor in case of phase failure in three-phase supply mains or failure of three-phase optoelectronic relay. Protective unit has three leads for monitoring voltage across motor phases and two leads for connecting three-phase optoelectronic relay in series with control circuit. In order to reclose device for normal operation upon elimination of phase failure three-phase optoelectronic relay should be deenergized for short time and then reclosed.
EFFECT: enlarged functional capabilities and operating reliability.
1 cl, 1 dwg
