When a three phase supply is applied to the stator windings, a voltage is induced in the rotor windings of the machine. The value of the magnetizing reactance X 0 is also very small in an induction motor. As we know that, in a transformer, the no-load current varies from 2 to 5% of the rated current, whereas in an induction motor the no-load current is about 25 to 40% of the rated current depending upon the size of the motor. This is because of the higher reluctance caused by the air gap of the induction motor. The total magnetizing current I 0 is considerably larger in the case of the induction motor as compared to that of a transformer. The no-load current I 0 is simulated by a pure inductive reactor X 0 taking the magnetizing component I µ and a non-inductive resistor R 0 carrying the core loss current I ω. The stator circuit model of an induction motor consists of a stator phase winding resistance R 1, stator phase winding leakage reactance X 1 as shown in the circuit diagram below: Approximate Equivalent Circuit of an Induction Motor.
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