PHASE-FAILURE PROTECTIVE GEAR FOR GROUP OF THREE- PHASE MOTORS Russian patent published in 1999 - IPC

FIELD: electrical engineering. SUBSTANCE: protective gear has two disturbance signal sensors inserted in each phase of supply mains, control unit, final member, and actuating element; disturbance signal sensor is built up of two reverse-sequence current filters inserted in three phases of supply mains; sensor outputs are connected to inputs of two rectifier bridges that function as inputs of control unit; outputs of rectifier bridges are connected through center taps of loads, first and second RC filters to inputs of first and second Schmitt flip-flops whose outputs are connected to inputs of third Schmitt flip-flop and through third RC filter, to fourth Schmitt flip-flop that functions as output of control unit, its output being connected to input of transistor switch controlling final member which turns off actuating element in emergency situations. EFFECT: improved reliability and sensitivity of device, simplified design. 4 dwg