Starting from the second half of the nineteenth century, ceramic and glass were the only insulating materials suitable for high voltage transmission lines. In the 1940s, with the advent of polymer materials, ceramics and glass are no longer the preferred insulating materials. European and American countries began to study polymer insulators. Then the physical properties, electrical properties, long-term reliability and optimal shape of electrical insulators are studied, and the productivity has been continuously improved.



Among the polymer materials that can replace ceramics and glass, silicone rubber has achieved practical results since the 1960s, and stands out among several polymers. Silicone rubber insulators have more advantages than ceramic insulators. First of all, it is light, easy to operate and safe; in addition, ceramic insulators are often troubled by breakage, and one kind of impact will damage them. Silicone rubber insulators, on the other hand, can withstand mechanical impacts such as vehicle collisions with poles.

Although other polymer materials have the advantages mentioned above, only silicone rubber will not cause too much pollution to the environment. Polymer insulators can be waterproof, so there will be no leakage and surface arc due to droplets falling. Silicone rubber insulator is a kind of durable material which can be used for a long time in harsh environment because its waterproof property is recovered faster than other polymer insulators.