Environmental impact on composite EPDM insulators

The environmental impact on composite ethylene propylene rubber (EPDM) insulators, exposed for many years to HVAC and HVDC under realistic conditions and natural pollution, was studied. The results show that the insulator material at the surface of the insulators undergoes a slow degradation process. The composite insulator surface loses successively its water-repellant properties, which initially make the organic composite insulators. The degradation of the insulator material depends both on the organic material composition and on the filler material. A thorough macroscopic and microscopic study of the EPDM insulator surface illustrates the differences of the surface state for insulators of different makes with different materials and fillers. The poor performance of aged composite insulators depends both on the design, in which often many interfaces are introduced, and on the organic material deterioration due to the environmental impact.<>