Comparative investigation of non invasive diagnosis methods for mechanical fault detection in induction motors

This paper presents a comparative investigation of different methods for non-invasive diagnosis of mechanical abnormalities in induction motors. Stator voltages and stator currents, as well as noise on these signals, are simulated first for a fault-free motor, and then for a motor with mechanical abnormalities. These signals are subsequently used to compute the instantaneous powers "P_ab", *P_cb", "P_abc". The last method to be examined is the current Park vector modulus, known as the extended Park vector approach "EPVA" method. Waveforms of these simulated signals were analyzed using the power spectral density transformation. The amplitude increase of these characteristic frequencies is used as a criterion in order to investigate noise-immunity of the five diagnosis methods, thus making possible their classification. As a result, lhe extended Park vector approach "EPVA" was observed to exhibit the highest noise-immunity. The "EPVA" therefore improves the reliability of diagnostics of induction motor drives.