Research on Identification and Localization of Internal Defects in Insulation Components Based on Ultrasonic Non-Destructive Testing Technology

• Main Authors: Dang, Linpei, Tian, Yi, Zhang, Fangyuan, Miao, Qingqing, Niu, Haotian, Huang, Xinbo
• Format: Conference Proceeding
• Language: English
• Subjects: Accuracy; Acoustics; Defect localization; Insulation; Insulation components; Location awareness; Mathematical models; Non-destructive testing; Power systems; Probes; Propagation; Switchgear; Testing; Ultrasonic shear wave
• ISSN: 2644-271X
• DOI: 10.23919/CMD62064.2024.10766220

With the rapid development of power systems, the insulation components inside high-voltage switchgear play an increasingly important role. Defects within these insulation components can lead to equipment failure and shutdown, resulting in economic losses or casualties. Therefore, the demand for non-destructive testing (NDT) of internal defects in insulation components is growing. This paper focuses on identifying and localizing internal defects in insulation components based on ultrasonic shear wave NDT technology. Firstly, since the propagation speeds of longitudinal and shear waves in different materials vary and are related to the material's Poisson's ratio, with most materials having a Poisson's ratio around 0.3, it follows from the wave equation that the shear wave speed is approximately half that of the longitudinal wave. Utilizing this principle, the speed of the shear wave can be calculated using the known material thickness and echo time from the longitudinal wave. Secondly, a shear wave propagation model is established. An angled wedge block with a 28° angle is placed between the ultrasonic probe and the material, causing the longitudinal wave to refract into a shear wave upon entering the material. Finally, since ultrasonic waves refract and reflect when propagating through materials with different acoustic impedances, causing changes in the echo waveform, a sudden change in the waveform upon encountering a defect allows for the derivation of a defect depth localization formula based on the time of the echo. Verification with three groups at different depths showed errors of 1.lmm, 1.6mm, and 1.0mm, respectively, demonstrating the practicality and accuracy of the defect localization method. This provides a theoretical reference for the NDT of internal defects in insulation components of power systems.