DEVICE FOR PROTECTION OF A C ELECTRIC MOTOR DRIVE Russian patent published in 1994 - IPC

FIELD: electrical engineering. SUBSTANCE: thyristor frequency converters 1 and 2 feed A C electric motor with m-phase stator winding divided into two three-phase groups 4, 5, 6 and 7, 8, 9. Windings of each group are star-connected and are separately coupled to outputs of frequency converters 1 and 2 via current pickups 10-15. Device includes logic 2AND gates 34-39 which outputs are connected to controlling inputs of frequency converters 1 and 2. Measuring outputs of current pickups 10-15 are linked to first inputs of corresponding comparators 40-45 which second inputs are connected to unit 46 for assignment of current setting. Outputs of comparators 40-45 are connected via INHIBITION gates 47-52 to second inputs of 2AND gates 34-39. EFFECT: enhanced efficiency and reliability of protection. 1 dwg