Circumventing the blocked rotor test when evaluating model elements of three phase induction motors

The paper proposes a method that may be used in lieu of the traditional but awkward blocked rotor test to evaluate the AC resistances and the leakage reactances of a polyphase motor. The method provides the element values of the five-element-per-phase Steinmetz model and the six-element-per-phase model of IEEE Standard 112-84. The test procedure is conducted with a freely-rotating motor operated at rated voltage, normal power line frequency and at power levels that may be a fraction of rated load of the machine being tested. Model elements are evaluated from the circular impedance locus of the Steinmetz model or a variation thereof adapted for the six-element-model. Data points on the locus are obtained with the machine operating as a motor and as an asynchronous generator