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 3 with m-phase stator winding divided into two three-phase groups 4, 5, 6 and 7, 8, 9. Windings of each group connected in star are separately linked to outputs of frequency converters 1 and 2 via current pickups 10-15. Protection device is provided with 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 coupled to first inputs of proper comparators 40-45 which second inputs are connected to unit 46 of current setting. Outputs of first group of comparators 40-42 are linked via 3 nor gate 47 to second inputs of 2AND gates 34-36 and outputs of second group of comparators 43-45 are connected via 3 nor gate 48 to second inputs of second group of 2AND gates 37-39. EFFECT: improved efficiency of protection. 1 dwg