Diagnosis of Failures in an Induction Machine (Effect of Number of Broken Bars)

Abstract

This article is part of the topic of surveillance, diagnosis and detection of anomalies of electric drives based on the squirrel cage induction machine in the presence of various faults in the rotor, more particularly the broken rotor bar fault. The spectral analysis of electromagnetic torque, speed and stator phase currents are an ideal tool for fault detection. On the one hand, it is shown that the broken rotor bar fault causes oscillations on the speed and the torque which result in vibrations in the rotation of the machine. On the other hand, for the stator current, the amplitude is no longer constant. These modulations which result in the presence of harmonics in the spectrum, where the appearance of the lateral rays in the vicinity of the fundamental which are used for the detection of broken rotor bar fault. To set up an effective detection technique, it is imperative to study the laws of variations of the amplitudes of these components as a function of the modulation frequency considered. Finally, the successful results obtained prove that the spectral analysis is able to detect the defect and the number of broken bars.