On-line current monitoring to diagnose airgap eccentricity in large three-phase induction motors-industrial case histories verify the predictions

An appraisal of on-line monitoring techniques to detect airgap eccentricity in three-phase induction motors is presented. On-line current monitoring is proposed as the most applicable method in the industrial environment and a novel analysis strategy is explained. The practical details of on-site case histories and analysis of the current spectra for each motor are presented. The results verify that the interpretation of the current spectrum proposed in this paper was successful in diagnosing airgap eccentricity problems in large, high voltage, three-phase induction motors