Deterioration of silicone rubber for polymer insulators corona discharge and effect of fillers

摘要

This paper describes deterioration phenomena and mechanisms on silicone rubber housings of the polymer insulators by corona discharges. The corona discharge was observed on the trunk portion the insulator tested in a fog chamber. Nitric acid andozone generated by the corona discharge were recognized on that trunk portion, which was discolored and became whitish. The discolored area was expanded with test period. Surface conditions and mechanical properties of six kinds of the silicone rubbercontaining ATH (Alumina Tri-Hydrate) and CaCO{sub}3 (Calcium Carbonate) as fillers, were investigated after immersion in 1N nitric acid for 96 hours.As a result, weight loss of test pieces containing CaCO{sub}3 and ATH fillers was more than those solely containing ATH. Cracks were observed on the surface of two specimens containing CaCO{sub}3 filler, and not observed on that not containing CaCO{sub}3 filler. This shows the cracks on the surface due to corona discharges are depending on the kind of the filler. The careful survey on the deterioration of the housing rubber due to the corona discharge should be done when we select the housing materialsfor the polymer insulators.