Spectral Analysis Using a Hall Effect Sensor for Diagnosing Broken Bars in Large Induction Motors

This paper presents the use of an invasive method specially applied for broken rotor bars diagnosis in large induction machines, considering the frequency domain analysis of the magnetic flux density variation in a low-cost Hall effect sensor. The proposed method is based on the Fast Fourier transform, or spectral analysis of the resultant magnetic flux density, to contribute to a crack and bar breaks diagnosis on large squirrel cage motors. More particularly, this paper considers the use of a method capable of overcoming some drawbacks from traditional diagnostic techniques, such as motor current signature analysis during operation at very low slip. The results from the computational simulation and some experimental tests are presented and could be considered for rotor failure diagnostics in induction motors.