Determination of Temperature Dynamics and Mechanical and Stator Losses Relationships in a Three-Phase Induction Motor Using Fiber Bragg Grating Sensors

Fiber Bragg grating (FBG) sensors are used to investigate the temperature dynamics of a three-phase induction motor under different supply conditions and also during startup. The temperature field distribution is monitored using eight uniformly distributed FBGs in the stator. Tests are performed with the motor running at no load and with intentional voltage disturbances in the motor feed. It is observed that the temperature distribution in the stator is not uniform either with or without a balanced voltage in the windings. An average level increase in temperature of 0.5 $^{\circ}{\rm C}$ is registered for all of the sensors and associated with the unbalanced voltage in the windings. The motor under the test is kept at synchronous speed and connected to a second motor to determine the temperature rise due to mechanical and stator losses. An increase in temperature of 4.5 $^{\circ}{\rm C}$ due to mechanical losses is registered as well as an increase of 15.5 $^{\circ}{\rm C}$ due to stator winding and stator iron losses.