Identification and Analysis of Micro Defects in Insulation Pull Rod Based on the Ultrasonic Method

During the manufacturing process of insulation rods, internal defects inevitably arise, causing partial discharges or breakdowns under electric field. The detection of internal defects before putting into operation can effectively reduce the occurrence of these situations. Ultrasonic method is considered as an effective method for detecting internal defects with its high efficiency and sensitivity. In this paper, different artificial defect samples are identified based on ultrasonic transmission method detection, and it is found that the internal air defects of fiber-reinforced epoxy composite parts at the millimeter thickness level can be sensitively identified, and the size of the defect area can be calculated based on the waveform and the probe wafer size. The problem of mixing the onset waveform with the bottom echo waveform when detecting thinner parts based on ultrasonic reflection method is solved, and the use of small size probes directly applied to the defect detection of GIS insulation rods is important to guide the operational reliability of insulation rods.