Accelerated Aging Study on Silicone Rubber Insulator with Contaminant Level and Fog Conductivity Variations

Polymeric insulators are widely used in transmission and distribution system in highly polluted areas due to great performance of hydrophobicity. However, further studies are needed to determine the degree of aging and degradation due to electrical and environmental stress to improve insulators’ quality. This paper examines the effects of accelerated aging and contamination on 20 kV line post polymeric insulators performance under various environmental conditions in the tropical region according to IEC 60507. The accelerated aging was conducted in 1000 hours period of UV exposure and immersion process according to ANSI C29-13 2018. Furthermore, kaolin and NaCl were used as daily contaminants respectively for non-soluble and soluble pollutions. Contaminant levels here were varied based on NSDD value. The experiments found that the higher the contaminant level and the conductivity of the fog, the RMS value of leakage current could reach three times higher. The surface conditions of the insulators were also affected by the decrease in the hydrophobicity class from class one to class three. Based on SEM/EDX result, the higher the contaminant level, the rougher surface it would be and it also could be explained with the increase of the Al/Si ratio from 0.54 to 0.96.