CONTROL GEAR FOR THREE-PHASE SLIP-RING MOTOR Russian patent published in 1996 - IPC

FIELD: electrical engineering. SUBSTANCE: closed loop is periodically created in rotor winding 2 each of whose phases is primary winding of single-phase current transformers 13,14,15 and 16,17,18. Secondary windings of each mentioned transformer are connected to inputs of control system 11 of pulsed control unit 12. Power inputs of the latter are connected to outputs of rectifier 3 through whose diodes phases A,B,C of rotor 2 are periodically connected to starting resistor 10. All components of control gear are placed in toroidal module fixed on shaft of motor 1. ON-time of rotor winding to starting resistor 10 depends of OFF-time of main thyristor 57 of pulse regulator 12. This enables motor starting (braking) at maximum starting torque within each current moment of time, raising its transient stability, and protecting it at heavy and durable dips of supply voltage. EFFECT: improved starting and braking characteristics of slip-ring motor due to automatic contactles and stepless variation of motor starting resistance. 20 cl