Rotor cage fault detection in induction motor using global modulation index on the instantaneous power spectrum

Electric motors play a very important role in the safe and efficient running of any industrial plant. Early detection of abnormalities in the motor will help to avoid costly breakdowns. Accordingly, this work presents a technique for the diagnosis of broken rotor bar in induction motor. Stator voltages and currents in an induction motor were measured and employed for computation of the input power of one stator phase. Waveforms of the instantaneous power were subsequently analysed using the Bartlett periodogram. The latter is calculated either with a rectangular window or a Hanning´s window. The evaluation of the global modulation index on the instantaneous power spectrum is used for fault detection. Several rotor cage faults of increasing severity were studied with various load effects. We show some experimental results to prove the efficiency of the employed method.