THREE-PHASE MOTOR PHASE-FAILURE PROTECTIVE GEAR Russian patent published in 1997 - IPC

FIELD: relay protection of three-phase motors. SUBSTANCE: protective gear has current transformers and three-phase rectifier bridge; in addition, it is provided with load resistor, amplifier, resistive divider with filter, comparator, capacitor, integrator, threshold element, and final element; starts of current transformer are connected to first and second inputs of rectifier bridge whose outputs are combined and connected to third input of rectifier bridge whose outputs are connected to load resistor and to input of amplifier whose output is connected to first input of comparator and through resistive divider with filter, to second input of comparator whose output is connected through capacitor and integrator to first input of threshold element whose output is connected to final element and to second input of threshold element. EFFECT: simplified design and improved reliability of protective gear. 3 dwg