RELAY PROTECTION DEVICE AGAINST INTER-WINDING FAULT OF ALTERNATING-CURRENT MOTOR STATOR WINDING Russian patent published in 2019 - IPC H02K11/00 H02H7/08 

FIELD: electrical engineering.

SUBSTANCE: use in the field of electric engineering for protection of three-phase electric motors against short-circuit between coils of one phase of the stator. Device comprises a protection unit made in the form of a measuring ring of turns of insulated wire so that its plane is perpendicular to rotor rotation axis, its geometrical center is located on this axis, and outputs of turns of said ring were connected to reacting element. According to the invention, the protection unit includes a double-winding toroidal transformer, in which a primary three-phase winding connected by a star is connected to a three-phase circuit supplying the motor, and outputs of secondary single-phase winding are connected in parallel and opposite to outputs of measuring ring connected to reacting element. Measuring ring is inserted into the U-shaped slot of the circular magnetic core installed inside the electric motor, besides, the core slot faces the motor stator winding located in the immediate vicinity of the front part.

EFFECT: higher sensitivity of protection against interturn faults inside winding of motor stator by unit built into machine body.

1 cl, 1 dwg