The evaluation of asymmetrically aging effect on silicon rubber insulators flashover voltage

Purpose This study aims to examine the effect of asymmetric aging (120 and 270 degrees) and symmetrical aging on the performance of silicone rubber insulators. The effects of different aged surfaces, pollution levels and humidity on flashover voltage (FV) have been experimentally investigated. Based on the laboratory results, a mathematical model has been presented to estimate the FV of insulators. Design/methodology/approach According to insulators constituent materials, polymer insulators are affected by environmental conditions, specifically by ultraviolet (UV) radiation. To investigate the effect of aging and environmental conditions on the insulator, two types of silicone rubber insulators were aged under UV radiation. Environmental conditions have been created by changing humidity in five levels and pollution in three levels. All tests have been performed on two virgins, two full aged and four asymmetric-aged insulators. Also, according to the effect of each parameter on the FV, a mathematical model has been presented for it. Findings UV aging causes the destruction of the silicon rubber insulator. The occurrence of flashover is one of the consequences of insulation failure. The enlargement of the aged surface has a nonlinear relationship with the reduction of the FV. By considering the effect of the aged surface, the accuracy of FV modeling can be increased. The results obtained from the mathematical model have shown that the estimation of the FV in different environmental conditions has an error of less than 5%. However, the modeling error is more than 15% if the effect of the aged surface is not considered. Originality/value In this work, it is intended to investigate the effect of asymmetric aging on the FV of the insulator. The obtained results have shown that the asymmetric aging surface is an important factor in changing the harmonic components of the leakage current, condition monitoring indicators and FV.