Detection of Air Gap Eccentricity on Three-Phase Induction Motor Using 3-Axis Digital ELF Gaussmeter

This paper presents air gap eccentricity detection performance using a 3-axis digital elf gaussmeter sensor on a three-phase induction machine. Most of the induction motor disturbances are related to eccentricity. In practice, static and dynamic eccentricities occur together. Therefore, it is necessary to have an early diagnosis or detection to deal with it to be detected and immediately corrected before a more serious problem occurs. The analytical approach for evaluating the performance of a three-phase induction motor under different eccentric conditions will be presented in this paper. The sensor used in this experiment is a coil-shaped sensor that can pick up flux signals that deviate from 3 different magnetic axes, namely the X, Y, and Z axis. This sensor is placed outside the stator with a 2-3 cm distance to not interfere with motor performance. The Fast Fourier Transform (FFT) method analyzes the frequency spectrum of the stray flux. In this study, failure detection was done by comparing the frequency spectrum of the flux deviating in normal motor conditions with an eccentricity of 0.2 mm. Experimental test results are introduced, including motors with air gap eccentricities as well as loading under unbalanced voltage conditions. Later, the stray flux on the three axes (X, Y, and Z channels) is measured and compared in the frequency domain. Detection performance is easy to detect under balanced voltage and no-load conditions, while in other conditions it is difficult to detect because it causes additional sidebands at the eccentricity frequency (fs ± fr).