The function of insulating material is to isolate the live parts with different potential in electrical equipment. Therefore, the insulation material should first have high insulation resistance and withstand voltage strength, and can avoid leakage, breakdown and other accidents. In addition, it should have good thermal conductivity, moisture resistance, lightning protection, high mechanical strength and convenient processing. According to the above requirements, the performance indexes of common insulating materials include insulation strength, tensile strength, specific gravity, expansion coefficient, etc.

 

According to their different chemical properties, insulating materials commonly used by electricians can be divided into inorganic insulating materials, organic insulating materials and mixed insulating materials. The commonly used inorganic insulation materials are mica, asbestos, marble, porcelain, glass, sulfur, etc., which are mainly used for winding insulation of motors and electrical appliances, bottom plates and insulators of switches, etc. Organic insulating materials include: shellac, resin, rubber, cotton yarn, paper, hemp, rayon, etc. most of them are used to make insulating paint, covering insulator of winding wire, etc. The mixed insulation material is a variety of molding insulating materials made of the above two materials after processing, which is used as the base and shell of electrical appliances.