Fault Diagnosis of Electric Low-Power Motors by Analyzing the Current Signal

Abstract To detect and localize faults occurring in the rotor of universal motors analysis of the current signal in the time and frequency domain is presented. The information about the condition of the rotor is contained mainly in the periodical components of the current signal. Because these harmonics are speed dependent and the speed is not constant, digitizing synchronously with speed is carried out. The method of linear prediction is used as a spectral modeling technique in which the current spectra are modeled by all-pole spectra. The coefficients of the linear predictors are the basis for automatic fault detection and classification.