Determination of long-term performance of polymeric insulators for distribution lines by salt fog method

Polymeric transmission and distribution line insulators are gaining market share as a result of improved tolerance to pollution, ease of handling and installation. However, the surface of insulating materials, such as silicone rubber, is subject to long-term degradation during outdoor use. Determination of long-term performance of the polymeric insulators is important, and some artificial aging test methods have been approved. We carried out field exposure and artificial salt fog aging tests for a type of polymeric distribution line insulator. The long-term performance was evaluated by comparing the cumulative leakage charge during the field exposure test and the salt fog tests, which demonstrated that comparison of leakage current properties of the field exposure tests and that of laboratory aging tests provided a basis for life estimation of polymeric insulators exposed to salt pollution.