Study on the ultrasonic method to detect large size insulated equipment for GIS

Abstract

The development of defects in basin insulators inside a GIS (gas-insulated metal-enclosed switchgear) could trigger partial discharges under long-term working voltage, threatening safe GIS operation. In this paper, the ultrasonic pulse-echo method was proposed to detect large-scale basin insulators. And an ultrasonic pulse-echo system was set up, including an ultrasonic generator, a transducer and so on. Among them, the ultrasonic generator has been improved to obtain the original ultrasonic waveform. Then ultrasonic tests were carried out on the thickness of large-scale basin insulators, and the type and appropriate frequency of the ultrasonic transducer was proposed. Besides, a void in the epoxy composite specimen was detected and located. The results showed that the ultrasonic pulse-echo method could penetrate 15mm $\sim70$ mm thick basin insulators, and the 1P20 transducer has a better effect on detecting defects than the 1.5P14. The ultrasonic pulse-echo method is feasible for detecting defects in large-scale basin insulators.