The application of modern signal processing techniques to rotor fault detection and location within three phase induction motors

Previous work at The Robert Gordon University has shown that faults within the rotors of large three phase induction motors, such as broken rotor bars, can be detected by monitoring and analysing the line current taken by the machine during a no-load starting transient. This line current has been shown to contain frequency components which are indicative of these fault conditions. Under transient conditions these components are however nonstationary in both the time and frequency domains. A variety of signal processing strategies applicable to time variant data such as the spectrogram, The Wigner Ville distribution and wavelet decomposition have been implemented and their success in detecting these non-stationary components evaluated. The most suitable of these techniques has been used to determine the occurrence and severity of motor faults. Preliminary work suggests that these techniques may also be used to detect frequency components indicative to the location of the fault