Study on the Aging Factors and Mechanisms for HTV in Composite Insulators in Hot and Humid Environments

Operating in hot and humid regions, composite insulators are subject to high temperature and high humidity for extended time, which accelerates the aging of silicone rubber. In this paper, for the purpose of exploring the influence of temperature and humidity on the aging of composite insulators, thermal oxidation, water soaking and boiling conditions were designed for simulating a high-temperature environment, a high-humidity environment and a hot and humid environment. It is found that high temperature will promote the aging of composite insulators, mainly manifested by the formation of silicone rubber inorganics and the decomposition of ATH. A high humidity environment contributes to water infiltration, filler precipitation and crack formation. When high humidity is combined with high temperature, significant loss of small molecules happened and the invasion of water is promoted, which facilitates the precipitation of fillers to form a fluffy powder layer.