FBG Thermal Sensing Features for Hot Spot Monitoring in Random Wound Electric Machine Coils

This paper investigates the key design and operational features of embedded fiber Bragg grating (FBG) sensing for thermal hot spot monitoring in random wound coils, such as used in low voltage electrical machines. To this end thermal experiments are performed on test wound coils embedded with FBG sensors to examine the vital application features of embedded sensor design, such as the sensor packaging material choice, in-situ calibration, sensitivity to vibration, and thermal response time. Measurement error rates are examined and quantified in representative practical tests. The reported results enable a much improved understanding of the performance implications of embedded FBG sensor design features and the attainable in-situ hot spot thermal monitoring performance in random wound coils.