DEVICE FOR DIFFERENTIAL PROTECTION OF ELECTRIC MOTORS AGAINST OVERLOAD

摘要

A device for differential protection of electric motors against overload comprises a current transformer and a switching device that are connected in-series with an asynchronous electric motor. A set of starting resistors is connected in-series to rotor windings. In parallel to rotor windings of the electric motor through a voltage rectifier bridge it is connected a primary winding of the DC transformer, in parallel to secondary winding it is connected a potential winding of a transformer differential relay, a current winding is connected to a current rectifier bridge united with secondary winding of current transformer.