Detection of rotor fault in three-phase induction motor in case of low-frequency load oscillation

This paper proposes a method for the separation of broken rotor bar failure and low-frequency load fluctuation in line-fed three-phase induction motor. In practice, the presence of load fluctuation at 2sfs\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$2sf_\mathrm{s}$$\end{document} has the same effect on a stator current of induction motor as a broken rotor bar fault. In such cases, the detection of broken rotor bar failure becomes difficult. To discern rotor fault and load oscillations, the analytical signal angular fluctuation (ASAF) method, which is a combination of Hilbert transform and the space vector angular fluctuation method, is used. The presented experimental results prove that low-frequency load oscillation and rotor fault can reliably be discriminated using the ASAF signal spectrum.