Induction Machine End-Winding Leakage Flux Monitoring Using FBG Magnetostrictive Composite Flux Sensor for Broken Rotor Bar Fault Detection

Whilst monitoring magnetic leakage flux has proven effective in detecting faults in induction machines its functionality and ultimately feasibility can depend on the choice of the applied magnetic flux sensing device. This study examines the application of a small size and power passive Fiber Bragg Grating (FBG) magnetostrictive composite magnetic flux sensor for localized magnetic leakage flux monitoring in the end winding region of an induction machine. The magnetic flux sensor's design, functional and installation features are presented first. A prototype sensor is then fitted in the end-winding region of an experimental test-rig induction machine to observe the frequency spectra of its magnetic leakage flux during healthy operating conditions and those including broker rotor bar faults. The results show that the reported method enables practical monitoring of the stray magnetic flux's frequency spectrum including the recognition of spectral components that can indicate the presence of a broken rotor bar fault condition.