Accelerated aging effect on high temperature vulcanized silicone rubber composites under DC voltage with controlled environmental conditions

Abstract Silicone rubber (SiR) insulators are considered as promising alternatives to conventional ceramic insulators for high voltage transmission networks. However, aging of SiR insulators is an issue when exposed to combined solar, environmental and electrical stresses. In this study, the effect of micro/nano-silica and micro-alumina trihydrate particles on multi-stress aging performance of silicone rubber with DC voltage was investigated. For this purpose, five types of composites were prepared by reinforcing nano-silica (2–6 wt%) and micro-silica/alumina trihydrate (20 wt%) particles into silicone rubber. These composites were exposed to various stresses combining ultraviolet radiations, humidity, heat and electrical in a specially designed test chamber for a duration of 5000 h. For aging assessment, the SiR composites were characterized by visual inspection, and through measurements of hydrophobicity classification, leakage current, scanning electron microscopy, fourier transform infrared spectroscopy and mechanical testing. Results showed that the composite test sample, S-2 (2 wt% nano-silica and 20 wt% micro-silica) exhibited minor surface roughness, highest hydrophobicity and least reduction in contact angle (16.44°). It also measured the lowest leakage current (3.39 μA), maximum tensile strength (3.43 MPa). The hydrophobic ( CH3) and backbone (Si O Si) groups of the test sample, S-2 also remained intact. The composite filled with 2 wt% nano-silica showed maximum resistance to multi-stress aging due to strong molecular interaction between nano-silica and silicone rubber. The outcome of this study will help electric utilities in finding superior alternates of conventional porcelain insulators for high voltage insulation applications.