Distribution of salt contamination in the course of fog chamber tests of polymer insulators

Contaminants are deposited on the insulator surface during salt fog tests. This provides a path for the leakage current to flow along the surface of the insulator. It is important to have an indication of the pollution accumulation in order to evaluate the test performance of a particular insulator. A good insulator is expected to have a smaller amount of contaminants deposited during the aging tests. The paper describes the test procedures, and presents data for various polymer (silicon rubber and EPDM) insulators. These insulators were tested under two different salt fog conditions. The positions of the insulators were either vertical or horizontal.