CONTROL GEAR FOR THREE-PHASE INDUCTION MOTOR Russian patent published in 1995 - IPC

FIELD: electrical engineering. SUBSTANCE: pushing START button 7 energizes coil of magnetic starter 2 over the following circuit: phase C, coil of magnetic starter 2, STOP button 6, START button 7, capacitor 8, phase B, which closes contacts 3,4,5. Current flows over circuit: phase C, coil of magnetic starter 2, STOP button 6, power contact 3, supply mains phase. Releasing START button 7 disconnects capacitor 8 from supply mains. In case of voltage failure in any of supply mains phases or fault in power contact 3 magnetic starter 2 will not operate. To switch off motor 1, STOP button 6 should be pushed. EFFECT: enlarged functional capabilities due to elimination of motor switching-on in case of phase failure or faulty contact in phase under check; improved reliability due to reduced quantity of power contacts. 1 dwg