INSTANTANEOUS POWER AS A MEDIUM FOR THE SIGNATURE ANALYSIS OF INDUCTION-MOTORS

Preventive maintenance of electric drive systems with induction motors involves monitoring of their operation for detection of abnormal elec trical and mechanical conditions that indicate, or may lead to, a fail ure of the system. Intensive research effort has been for sometime foc used on the motor current signature analysis (MCSA). The MCSA techniqu es utilize the results of spectral analysis of the stator current. Rel iable interpretation of the spectra is difficult, since distortions of the current waveform caused by the abnormalities in the drive system are usually minute. In this paper, an alternate medium for the motor s ignature analysis, namely the instantaneous power, is proposed. By the oretical analysis, computer simulations, and laboratory experiments, i t is shown that the instantaneous power carries more information than the current itself. Utilization of the instantaneous power is thus enh ancing the reliability of diagnostics of induction motor drives.