In the early years, insulators were mostly used in power poles. With the development of science and technology, they gradually developed in the end of the high-type high-voltage wire connecting tower, where a lot of disk-shaped insulators were hung. They were used to increase the creepage distance and were usually made of glass or ceramics, which were called insulators. Insulator in overhead transmission lines with two basic role, namely support wire and prevent the current back, these two functions must be guaranteed, insulator should not change due to environmental and electrical load conditions lead to various electrical and mechanical stress and failure, or else there won't have a significant role in the insulator, will damage the whole line of use and operating life.
Composite insulator is a special insulating control which can play an important role in overhead transmission line.
The fracture of composite insulators will lead to serious power accidents. Therefore, the research on the fracture mechanism of composite insulators and the corresponding preventive measures has important scientific significance and engineering value.
In several accidents of composite insulator's abnormal fracture in recent years, the fracture form of the fractured core bar is completely different from the known brittle fracture and common fracture form of composite insulator. The characteristics of this new composite insulator abnormal fracture include:
1) serious deterioration of the manhole manhole (the macroscopic section of the manhole manhole is not smooth, the texture of the manhole manhole becomes crisp, and the manhole is shaped like withered wood, the manhole is powdered, and the glass fiber and epoxy resin matrix are separated from each other, etc.);
2) interface failure between the silicon rubber sheath and the glass steel core near the fracture of the core;
3) the interface failure area between the silicone rubber jacket and the glass steel core is mostly connected with the high-pressure end through carbonization channel;
4) several transverse electroerosion holes developed from inside to outside appear on the sheath;
5) there is abnormal temperature rise phenomenon before the insulator is broken.