Air-gap eccentricity is commonly occurred in large induction motors, especially submersible motors. Based on this failure, a more accurate curved eccentricity model is established and current analysis of the faulty machine is conducted in this paper. To carry out calculation, winding function method is proposed aiming at calculation of the inductance matrix in the multi-loop model and theoretical derivation is also presented. A curved eccentricity model is set up by simulating the deflection of the shaft and such model is applied to prototype (1200 kW submersible motor). By analyzing harmonic characteristics in line current, the result proves feasibility of current monitoring on curved eccentricity.
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