Effects of Artificial Tropical Climate Aging on Insulation Performance of Silicone Rubber Polymeric Insulators

Porcelain insulators have been used in transmission and distribution lines since long time ago. There are so many reports of system failures caused by porcelain insulator failures especially in highly polluted areas. Due to superiority in repel of contaminated solution, polymeric insulators set to replace the ceramic insulators in transmission and distribution lines. The objective of the current paper is to study effects of aging on leakage current characteristics and housing conditions of silicone rubber polymeric insulators under artificial tropical climate. Polymeric insulator sample was put in a chamber and have been exposed to ultraviolet radiation by UV lamp and penetrated in a vessel contain contaminant solution according to ANSI C-29 13-2000. The electrical properties as well as changes on the surface were investigated by measuring magnitude, waveform, THD, and cross product of leakage current. Visual observation of the hydrophobicity class of silicone rubber’s sheds was observed using a camera. To know the relations of hydrophobicity class with leakage current characteristics, samples were tested in a chamber under variety of salt-fog and pollution conditions according to IEC 60507. The housing conditions of silicone rubber polymeric insulator were investigated using SEM-EDX method. Experimental results indicated that UV radiation, corona activity, and contaminant solution are greatly affect the aging of the insulators. In addition, combination of high pollutant and humidity extremely increase the magnitude and THD of leakage current especially for sample after aging.