Faults and failures of induction machines can indeed lead to excessive costs, hence, there is a strong demand in the industry for adopting diagnosis techniques to assess and evaluate current condition of electrical ma...Faults and failures of induction machines can indeed lead to excessive costs, hence, there is a strong demand in the industry for adopting diagnosis techniques to assess and evaluate current condition of electrical machines. Eccentricity related faults as well as clutch wobbling constitute major portions of the faults related to induction motors. This paper presents the effect of clutch wobbling and mixed eccentricity on induction machine stator currents and the possibility of distinguishing between each ailment via comparing the abnormal harmonics contained in stator current spectrums in each case. In this paper, the current spectrum of a four pole-pairs, 550 kW, induction machine were calculated for the cases of full symmetry, clutch wobbling, and mixed eccentricity. The calculations involve integration of 93 electrical plus four mechanical ordinary differential equations. Electrical equations account for variable inductances affected by slotting and eccentricities. The calculations were followed by Fourier analysis of the stator currents. Zooms of the current spectrums, around the 50 Hz fundamental harmonic as well as of the main slot harmonic zone, of both calculated and measured currents are included. The spectrums presented in this paper rely on calculations that are performed with dedicated software which is owned by AGH University of Science and Technology.展开更多
文摘Faults and failures of induction machines can indeed lead to excessive costs, hence, there is a strong demand in the industry for adopting diagnosis techniques to assess and evaluate current condition of electrical machines. Eccentricity related faults as well as clutch wobbling constitute major portions of the faults related to induction motors. This paper presents the effect of clutch wobbling and mixed eccentricity on induction machine stator currents and the possibility of distinguishing between each ailment via comparing the abnormal harmonics contained in stator current spectrums in each case. In this paper, the current spectrum of a four pole-pairs, 550 kW, induction machine were calculated for the cases of full symmetry, clutch wobbling, and mixed eccentricity. The calculations involve integration of 93 electrical plus four mechanical ordinary differential equations. Electrical equations account for variable inductances affected by slotting and eccentricities. The calculations were followed by Fourier analysis of the stator currents. Zooms of the current spectrums, around the 50 Hz fundamental harmonic as well as of the main slot harmonic zone, of both calculated and measured currents are included. The spectrums presented in this paper rely on calculations that are performed with dedicated software which is owned by AGH University of Science and Technology.
