Fig. 1. Schematic diagram of the working principle of fiber optic grating sensor

Fig. 2. Schematic diagram of experimental system

Fig. 3. Surface temperature measurement results of composite insulators

Fig. 4. Thermal image segmentation results of composite insulators

Fig. 5. Division results of composite insulator structure area

Fig. 6. Identification results of abnormal hot spots on the surface of composite insulators

Fig. 7. Thermal response curve of abnormal hot spots