Vibration measurement of Induction Motor under dynamic eccentricity using optical fiber Bragg grating sensors

The vibration in Three-Phase Induction Motors (TIM) is due to mechanical and electrical forces existing during the motor operation. Vibration problems in induction motors can be extremely frustrating and may lead to greatly reduced reliability increasing the maintenance cost. The vibration was measured using fiber Bragg gratings (FBG) installed inside the motor between two stator teeth. The vibration frequencies in TIM are predicted using a model of the forces present in the air gap considering a static and dynamic rotor eccentricity. Two FBGs were positioned between two stator teeth, separated by 120° from each other. The analysis of the vibration spectrum at 60 Hz motor power supply presents the frequencies 60 Hz, 120 Hz, 180 Hz and 240 Hz. This combination of the mechanical and electrical frequencies continue to appear even when the motor electrical supply frequency is reduced by half. The measurement present in this paper can be used to determine some TIM parameters, like the effect of the motor power supply on its vibration signal and also be used like a potential maintenance tool for predictive purposes with high efficiency to continuously monitor the TIM.