Non-destructive testing of internal defects in composite insulators using microwave technique

This paper introduces a kind of non-destructive detection method on detecting internal defects of composite insulator based on the microwave reflection method. The method emits the microwave to the sample, extracts the reflection wave with directional coupler, and detects its intensity. Flat plate shape samples made of silicone rubber and epoxy resin were used to study the stability the system, and the detection effect on defects of different sizes. On the other hand, the cylindrical shape samples were used to summarize the regularity of detection results on insulators without defects, and the detecting effect on the samples containing defects. Moreover, influence of surface contamination on this method was studied through experiments. The research results showed that the microwave detection method could detect the internal defect of composite insulators with a size of millimeter, and the surface contamination had a little influence on the detection.