Fiber Bragg grating sensing applications in temperature monitoring of three-phase induction motors

This paper presents an analysis of simultaneous temperature and electrical parameters measurements in a three phase induction motor (TIM). The electrical parameters, namely voltage and current in the motor windings, were measured with Hall effect sensors and the temperature in the stator slots were monitored using fiber Bragg grating sensors (FBG). In the performed temperature analysis, two sets of sensors were used, containing four FBG in each fiber. Eight FBG sensors were uniformly distributed in the TIM stator. A special encapsulation of the sensor was elaborated to minimize mechanical disturbances in the fiber due to motor operation. Tests were performed with motor running at no load and with intentional voltage disturbances in the windings produced at every 15 minutes periods. It was observed that the temperature distribution is not uniform in the TIM stator either with or without a balanced voltage in the windings. A mean level increase of 0.5°C in temperature was registered in all of the sensors when there is a lack of balance in the voltage windings.