In the early days, insulators were mainly used in utility poles. With the development and needs of society, they were gradually applied to high-voltage high-voltage wire connecting towers, mainly used to increase the creepage distance (the creepage distance refers to between two conductive parts, or one The shortest space distance measured between the conductive parts and the equipment and the easily accessible surface along the surface of the insulating material. In order to prevent dust and other contamination from adhering to the surface of the insulator, the formed passage is broken by the voltage across the insulator, that is, creepage. Depending on the degree of contamination, the weight In dirty areas, the creepage distance is usually 31 mm/kV.), usually made of glass or ceramic.

Insulators have two fundamental functions in overhead transmission lines: supporting the conductors and preventing current from returning to the ground. In order to ensure these two basic functions, the insulators should not fail due to various electromechanical stresses caused by changes in environmental and electrical load conditions. Otherwise, it will damage the use and operating life of the entire line.

According to different standards, insulators have different classifications, as follows:

1. According to whether it is broken down, the insulator is usually divided into a puncturable type and a non-breakable type.

2, according to the structure, can be divided into column (pillar) insulators, suspension insulators, anti-fouling insulators and casing insulators.

3, according to the application, can be divided into line insulators and power stations, electrical insulators. Among them, the puncturable insulator used for the circuit has a pin type, a butterfly shape, a disc type suspension type, and the non-breakable type has a cross arm and a rod type suspension type. The puncturable insulators for power stations and electrical appliances have pin-type struts, hollow struts and sleeves, and non-breakable type of rod-shaped struts and container porcelain sleeves.

4, insulators used in overhead lines, commonly used are pin insulators, butterfly insulators, suspension insulators, porcelain crossarms, rod insulators and tension insulators.

Insulators commonly used in the industry are: ceramic insulators, fiberglass insulators, composite insulators, and semiconductor insulators.