It has been shown that the occurrence of shorted turns and phase imbalanced in the stator winding of induction motors cause predictable harmonics to appear in the spectrum of line currents and in the axial leakage flux. The authors show how such beating can itself be used as a measure of condition of the machine. The proposed technique extracts the changes in phase caused by the beat frequencies, and uses them to develop an alternative method of illustrating spectral changes. A simple computer based monitor has been developed using this technique, and results obtained using it are presented.
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