DC insulators generally have a longer creepage distance than AC stain-resistant insulators, and their insulators have higher bulk resistivity (not less than 10 Ω · m at 50 ° C). Sacrificial electrodes (such as zinc sleeves, zinc rings).
Type A insulators and B insulators. Type A is a non-breakdown insulator, and its dry flashover distance is not 3 times the dry breakdown distance (cast resin) or 2 times (other materials): Type B can breakdown insulators, and its breakdown distance is less than 1/3 (cast resin) or 1/2 (other materials) of the dry flashover distance.
The dry flashover distance of the insulator refers to the shortest distance through the air along the outer surface of the insulator; the breakdown distance refers to the shortest distance through the insulating material of the insulator.
The main function of an insulator is to achieve electrical insulation and mechanical fixation, for which various electrical and mechanical performance requirements are specified.