Rotor Cage Fault Diagnostics in Three-Phase Induction Motors, by the Instantaneous Phase-Angle Signature Analysis

Detection of broken rotor bars has long been an important but difficult job in the detection area of motor faults. The characteristic frequency components of a faulted rotor in the stator current spectrum are very close to the power frequency component but by far less in amplitude, which brings about great difficulty for accurate detection. In this paper a new detection method based on the instantaneous phase-angle signature analysis is proposed for the diagnosis of rotor cage faults in operating three-phase induction motors. For that purpose, a mathematical model based on the winding function approach is used in order to simulate this type of fault and experimental tests are carried out on an induction motor with several faulty rotors. Simulation and experimental results are presented to show the merits of this novel approach for the detection of cage induction motor broken rotor bars.