History Of Composite Insulators

In the 1980s, with the support of the national Seventh Five-Year Plan, the Institute of Hydraulic and Hydroelectric Engineering and other institutions began research and development of composite insulators. Both institutions used high-temperature vulcanized silicone rubber for the shed material, but employed different technical approaches to the connection methods of the fittings and epoxy fiberglass core rods. The university used an internal wedge structure, while the Institute of Hydraulic and Hydroelectric Engineering used an external wedge structure. The technological achievements of both institutions were transferred to enterprises and transformed into productive forces.

Initially, power operation departments had doubts about the performance of composite insulators and were very cautious about grid-connected operation, only conducting live-line tests on a small number of test units on less important lines with voltage levels below 110 kV. In 1990, a large-scale and severe flashover accident occurred in North China. The composite insulators tested demonstrated excellent flashover resistance, which was well-received by power operation units. Many departments actively adopted this new technology, expanding the scale and scope of trial operations, greatly improving the flashover resistance of transmission and distribution lines and reducing the workload of line cleaning, thus gaining popularity among power operation units. After several years of operation and evaluation, the power authorities have recognized composite insulators as a new technology for preventing flashover and have begun to apply them in voltage levels above 110kV.