ANALYSIS OF RATED POWER DECREASING FOR ASYNCHRONOUS MOTOR WITH ROTOR AC EXCITATION

The paper is one of the main ways to modernize mine hoist installations based electric wound rotor induction mo-tors. Also, the basic wiring diagram of converters for speed control of induction motors, the advantages and disad-vantages of their application are considered. Wiring diagram of the wound rotor induction motor with a double-fed machine scheme is proposed. Frequency converters are included in the circuit of the stator and the rotor circuits, while for the formation of the excitation field cheaper thyristor frequency converter is used. Further analyse of reducing of the nominal capacity of the asynchronous machine with AC excitation is made. The reasons of reducing elec-tromagnetic torque machines, as well as the feasibility of using frequency converters from the stator and rotor are considered. The analytic dependence of the electromagnetic torque and rotor current double-fed machines are con-cluded. Expression obtained as a function of the overload capacity of the motors, as well as the timing advance function are obtained. Percentage ratio of incidence of the motor at the rated current of the rotor as well as increasing the current while providing nominal load are calculated. The recommendations for the using of the proposed drive system when upgrading electric mine hoist installations are made.