Patent ID: 6128583
Filing Date: 2000-10-03
Classification: G01R

Abstract:
A method of evaluating stator condition of a polyphase induction motor, the motor including a number of pole pairs, by using an electrical signature of the motor, comprising the steps of:(a) simultaneously sensing an instantaneous current signal supplied to the motor as a function of time for three electrical phases of the motor;(b) simultaneously sensing an instantaneous voltage supplied to the motor as a function of time for three electrical phases of the motor;(c) calculating an effective negative sequence reactance and resistance directly from the measured voltages and currents for each phase of the motor, without performing intermediate calculations of the negative sequence voltage or current;(d) comparing the effective negative sequence reactance (X.sub.2) and the effective negative sequence resistance (R.sub.2) to predetermined values whereby a predetermined difference between either X.sub.2 and R.sub.2 and the respective predetermined value is indicative of a stator winding fault.