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Stator current of induction motor is analysed at single phasing by measuring phase angle, symmetrical components, Skewness, Kurtosis and harmonic distortion in Park plane. Diagnosis of single phasing of induction motor has been achieved by sequence components and stator current based pattern assessment. Distinct phase shift from 120°to 180°is observed between healthy phases. Patterns are formed using line currents and single phasing is assessed by using rule sets developed from features extracted from those patterns. Experimental result agrees with rule set and result obtained by assessment using sequence components. Then assessment is done by analysing wavelet decomposition based Skewness and Kurtosis of stator current in Park plane. At last, area based approach is used for assessment of single phasing and different distortion factors because of harmonics in Park plane are assessed. Accuracy increases with the increase of sampling rate of data acquisition system and use of Park plane has reduced computation effort by two-thirds. Thus single phasing is detected by sequence components supported by pattern formation and feature extraction and then harmonics during single phasing are assessed by wavelet decomposition and area-based approach in Park plane.

This study deals with measurement of harmonic distortion and Skewness of stator current in Clarke plane at crawling of induction motor. Three-phase current signals have been transformed into Clarke plane. Dominancy of seventh harmonic is observed by assessing maxima and minima of stator current Concordia in Clarke plane. Specific reference signals having sinusoidal nature and different frequencies are defined and then areas covered by the real system data with the reference signal have been determined, wherefrom individual contributions of fundamental waveform and harmonic components are measured separately and total harmonic distortion factors are determined. Then wavelet decomposition of stator current is done in Clarke plane, wherefrom, signals are assessed with the help of Skewness of approximate coefficient in Clarke plane. Significant differences are noted between those parameters found during crawling and that of normal condition which may be useful in detection of such fault.