Dynamic analysis of mixed eccentricity signatures at various operating points and scrutiny of related indices for induction motors
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abstract
Load variation along with static and dynamic eccentricities degrees is one of the major factors affecting the dynamic behaviours of eccentricity signatures which is utilised for precise mixed eccentricity fault diagnosis. Without taking the effect of load variation into account properly and just by considering the change in the static and dynamic eccentricity degrees, inaccurate fault detection is acquired. This is of noticeable effects that load variations have on side-band components that are used as fault detection indices. These indices are extracted from the current spectrum of healthy and faulty motor. In this paper, all these factors are dealt in a unified framework by analysing various combinations both theoretically and experimentally. An incisive approach is developed to recognise mixed eccentricity and determine the static and dynamic eccentricities degrees individually at different load levels literally. In order to evaluate the impact of load-dependent indices on eccentricity detection and fault-severity estimation, a systematic relation between each other and eccentricity degree is proposed. Correlation coefficient and mutual information are applied to assess abilities of the obtained indices for eccentricity detection in terms of their relation to static and dynamic eccentricities, their degrees and dependency on the load of motor. The classification results indicate that the elicited indices estimate the eccentricity type and degree exactly. Since, the accuracy of calculated stator current, computed from simulated motor, has considerable effects on precise fault diagnosis, time-stepping finite element method (TSFEM) is employed to model the healthy and faulty induction motor. The Institution of Engineering and Technology 2010.
