Composite insulator, also known as synthetic insulator, was first born in Germany. It was successfully developed by Hearst Company of Germany in 1967 and put into operation on 123kV line. It has more than 30 years of operation experience. Composite insulators have been rapidly developed in the United States, Britain, France, Italy, Russia, Japan and other countries, and have been widely promoted worldwide. The production of composite insulators in China started relatively late. In 1974, epoxy resin insulators were developed by the National Railway Research Institute. In 1978, silicone rubber composite insulators were developed, and thousands of products were put into trial operation, which gained valuable operational experience. In the past 10 years, the use of composite insulators in China has grown rapidly. It has ranked second in the world in 1998. Since 2000, it has been used extensively on ±500kV DC transmission lines. There are currently about 6 million composite insulators operating in China’s power system.

Silicone rubber composite insulators are generally synthesized from two or more organic materials. They are light in weight, high in strength (core rod), high in impact resistance, high in flashover resistance, easy to install, no need to measure zero, lightning strike, and no flashing. The advantages of insulation breakdown, composite insulator consists of mandrel, sheath, shed skirt, end fittings and accessories, which is the first choice for heavy pollution.

The original rubber of silicone rubber has low mechanical strength. The “peroxide” is used as a vulcanizing agent. The vulcanization temperature is 150 ° C ~ 180 ° C. The organic oxide is decomposed and crosslinked with the rubber organic side groups to form a vulcanized silicone rubber. (ie high temperature silicone rubber). Silicone rubber is added to the meteorological method of white carbon black (the cost is reduced by the precipitation method of white carbon black, its strength is greatly reduced) to ensure the tensile and tear strength of silicone rubber.

Adding a certain proportion of “aluminum hydroxide fine powder” to the silicone rubber can significantly improve the arc burning resistance of the silicone rubber.