The function of medium voltage insulators is to isolate the charged parts with different potential in electrical equipment. Therefore, insulating materials should first have high insulation resistance and voltage strength, and can avoid leakage, breakdown and other accidents. Secondly, it has good heat resistance and avoids aging and deterioration due to long-term overheating. In addition, it should have good thermal conductivity, moisture and lightning resistance, high mechanical strength and convenient processing. According to the above requirements, the common performance indicators of medium voltage insulators are insulation strength, tensile strength, density and expansion coefficient. According to the national standard GB 2900.5, the medium voltage insulator material is defined as the material used to insulate the device in electricity. It is the material that prevents the current from passing through. Its resistivity is very high and the leakage current can be neglected.
Medium-voltage switchgear is widely used in many fields. The insulating materials used vary in form and variety. According to incomplete statistics of the State Grid, insulation failure accounts for more than 30% of all kinds of accidents. In product design, medium voltage insulator
materials should be selected according to the characteristics of the product. The most suitable material with uniform safety, new economy and environmental protection should be selected.