Aging Mechanisms and Evaluation Methods of Silicone Rubber Insulator Sheds: A Review

So far, silicone rubber (SiR) insulators are widely used in the power industry all over the world, due to their outstanding insulation properties and high reliability. In practice, some of the insulators are applied in remote places with harsh environmental conditions such as high altitude, high temperature, high humidity, etc. Herein, the currently existing aging mechanisms are investigated, and some novel insights into these testing and evaluation methods are proposed. Via the investigation, it was found that thermal oxygen aging tends to occur when insulators are exposed to an environment surrounded by hot air. To analyze the different aging mechanisms of SiR insulator sheds, four types of aging testing and evaluation methods are systematically summarized based on the surface's structural, chemical, optical, and electrical properties. The conclusion is that nondestructive and noncontact methods, such as hyperspectral imaging (HSI), along with the multisource information fusion methods, are becoming increasingly popular in the assessment of SiR insulator sheds aging. These research efforts provide assurance for reducing the incidence of pollution flashover accidents in power transmission lines and ensuring the safe and stable operation of power transmission and transformation equipment.