INDUCTION MOTOR TURN-TO-TURN FAULT PROTECTION METHOD Russian patent published in 2007 - IPC H02H7/08 

FIELD: protection of induction motor stator winding against turn-to-turn fault.

SUBSTANCE: proposed method includes measurements of instant current and voltage across motor terminals, their conversion into voltages proportional to current and voltage, measurement of motor slip, recording of obtained signals proportional to current and voltage which are used to evaluate initial phase of transient and initial current, calculation of next instant currents at initial values of equivalent active resistance and equivalent inductance of motor, comparison of calculated instant currents with respective recorded values, evaluation of their difference, and variation of equivalent active resistance and equivalent inductance depending on this difference until difference between recorded and calculated values of instant current is brought to minimum, comparison of equivalent active resistance and equivalent inductance obtained in the process at measured slip with admissible values, and generation of OFF-operation signal in case these values exceed admissible ones.

EFFECT: enhanced protective-gear selectivity and speed of response.

3 cl, 8 dwg