Ultrasonic Detection Of Internal Artificial Defects In A Composite Insulator

Composite insulators were used more and more popular in the transmission lines forits excellent ability of anti-pollution flashover. Existing Insulation preventive test methodscannot effectively detect the inner defects of composite insulators which become hiddendanger to power grids. This paper presents a non-destructive testing method to inspecttypical internal defects of composite insulators by using the ultrasonic phased array flawdetector. Ultrasound scan images is used to determine the inner defects of compositeinsulator. The images are produced by superimposed ultrasonic signals which aretransmitted by multiple independent bimorph in the ultrasound transducer spreading in thedifferent interface. The main research content is as follows:(1) Make artificial defects in the hollow composite insulator silicon rubber layer:middle bubble, central section defects and debonding defect. Using conventional ultrasonicphased array probe to detect of the internal defects of composite hollow insulator.(2) Design special probe for detecting internal defects of suspended compositeinsulators for their smaller rod diameter. Make three kinds of typical internal defects: coreperforation defect, embedded strip defects and interface blowhole, to simulate the actualdefects of the broken core, interfacial debonding and bubble of the interface.(3) Based on above two sets of experiments, using ultrasonic phased array technologyto detect favor insulators in the actual operation.Through the comparative study of composite insulators by phased array scanningimages under different defects, verify the feasibility of the phased array ultrasonic fordetection of internal defects in composite insulators. The characteristics of phased arrayscan images about various inner defects of insulators and detection efficiency have beensummarized. This paper provides a new way for nondestructive testing of internal defectsin composite insulator.