Improvement of monitoring and diagnosis of broken bars/end-ring connectors and airgap eccentricities of squirrel-cage induction motors in ASDs using a time-stepping coupled finite element-state space technique

This paper discusses how a time-stepping coupled finite element-state space (TSCFE-SS) modeling technique can be utilized in diagnostic techniques to improve condition monitoring and diagnosis of induction motor rotor abnormalities of broken bars, broken connectors and airgap eccentricities. This investigation shows that application of the TSCFE-SS modeling technique can facilitate monitoring the characteristics of several frequency components as opposed to merely previous monitoring of sideband frequency components associated with the fundamental in motor phase current waveforms. The results presented in this paper clearly illustrate the possible potential use of the modeling technique for improvement of present diagnostic techniques in which diagnosis of broken bars, broken connectors and airgap eccentricities is restricted to identification of the sidebands associated with the first-order (fundamental) component in phase current waveforms. In addition, the results further demonstrate that database generation for various possible faults prior to their occurrences can be readily achieved using this modeling technique.