Measurement of Residual Stress in GIS Basin Insulators by Using Ultrasonic Longitudinal Critically Refracted Wave Method

The residual stress could be produced during the curing process of GIS basin insulators. The coupling of residual stress and external stress may cause stress concentration, which threaten the safe operation of the insulators. In this paper, the method for detecting residual stress of a 252kV GIS basin insulator by critical refraction longitudinal wave (LCR) is presented. The residual stress detection system is built. The main frequency of excitation and receiving probe is 2 MHz. The ultrasonic velocity of epoxy resin standard sample is measured. Two checkpoints on the basin insulator are selected for the circumferential residual stress detection with a distance of 5 mm. The results show that ultrasonic velocity of the standard sample is 2927 m/s. The ultrasonic propagation time of the two checkpoints is different. Near the central conductor, the ultrasonic velocity is 3399 m/s and the compressive residual stress is 0.38 MPa. The ultrasonic velocity is 3073 m/s and the compressive residual stress is 0.12 MPa far away from the central conductor.