An Accurate Determination of Induction Machine Equivalent Circuit Components

This paper is to propose a procedure for the determination of complete components of the induction machine equivalent circuit at various operating conditions, considering the effect of skin and temperature on the stator winding, rotor winding, and iron core losses calculations. Also, the variation of temperature on speed (slip), the variation of speed on mechanical (friction and windage) losses, magnetizing saturation effect, slip effect on the iron core losses and skew effect on the machine parameters are considered. Besides these parameters effect, the method of equivalent circuit parameters determination requires measurements of supply voltage per phase, stator current per phase from no-load to full-load points, stator D.C. resistance per phase at ambient temperature, no-load test at different supply voltages from 125% down to 25% and a locked-rotor test at a variable frequency from 100% down to 10% of rated. In this method, the air-gap magnetizing voltage, the machine power factor, the stator iron core resistance, the rotor iron core resistance, the stator stray loss resistance, and rotor stray loss resistance are accurately determined to achieve excellent accuracy using this proposed methodology.