Microwave Detection Technology for Internal Defects of Composite Post Insulators

Composite post insulators are prone to internal defects due to leakage current during the operation and harsh outdoor conditions. Microwave detection is an effective nondestructive testing method. The propagation of microwave at the insulating material interface is affected by the dielectric properties of the media. The composite post insulator is a multi-interface structure and has more interfaces when there are defects inside. Therefore, the reflected microwave of the composite post insulators can be analyzed to evaluate the internal interfaces distribution of the sample. We study the propagation law of microwaves in composite post insulators and proposes a defect detection method. The method converts reflected microwaves into energy signals and compares them with reference values. A portable microwave detection equipment is designed. The device can realize the generation, detection, and processing of microwave signals. It is equipped with software for data analysis and data visualization. The sample with debonding defects on site was collected and the nonconductive defect, semiconductive defects, and conductive defect were artificially produced. The effectiveness of the detection method and the device was verified by experiments with the defects inside the sample.