Induction motors broken bar and eccentric gap on-line detection using motor signature current analysis under laboratory and field conditions

Design and application of an on-line diagnostic system for squirrel cage induction motors based on inductive acquisition and sideband analysis of phase current. Controlled faults were produced on a squirrel cage motor under laboratory conditions to confirm and assess sideband diagnostic sensibility prior to field-testing. Those induced faults included broken bar and eccentric gap to evaluate current phase modification according to faults severity. Frequency and time domain phase current study allows sideband analysis and its correlation to motor diagnosis. Details of experimental set up implemented on a PC based digital acquisition system are described on the text. Successful implementation of a sideband current analysis for installed high capacity motors during normal operation is presented.