Study on the Feature Recognition of Interfacial Defects in Composite Insulator Using Low Energy Chirp Pulsed Radar Thermography

The insulation performance of composite insulator is reduced due to the possible defects such as air gap, crack and delamination, which leads to serious power grid accidents. Interfacial defect is one of the main structural defects of composite insulator. In this paper, a low-energy active infrared thermography (AIT) method based on chirp pulsed radar (CPR) excitation is studied. And a platform is built to test the silicone rubber (SIR)- epoxy resin sample with artificial flat bottom holes. Use CPR signal to excite and analyze the results. Principal component analysis (PCA), one of the post-processing characteristic extraction algorithms is used to process the thermal wave response signal of the sample to improve the detection accuracy of defects. The signal-to-noise ratio (SNR) of defects is used as an indicator to evaluate the effectiveness of defect detection. The results of pulse thermography (PT) of the sample are used for comparison to verify the detection effect of CPR signal excitation on deep defects.