Study on the AC Flashover Voltage of Corona-Aged Epoxy Resin Insulating Surfaces Under Contamination and Condensation

Abstract

In this article, bisphenol A epoxy resin (E-51) as A group, Methyl tetrahydrodiphosphonic anhydride (MTHPA) as A curing agent, and acid anhydride crosslinking system epoxy resin samples were prepared. By establishing a condensation discharge platform, the surface condensation of epoxy resin was studied by temperature, relative humidity, and filth degree. The influence of hygrothermal corona aging on the surface flashover voltage of epoxy resin in the condensation state was analyzed by static contact Angle, scanning electron microscope, and infrared spectrum. The results showed that with the increase of temperature difference, relative humidity, and fouling degree, the surface condensation quality of epoxy resin also increased, and the temperature difference had the greatest effect on the surface condensation quality. With the increase of aging time, the static contact Angle decreased from 83.8° to 36.7°. At the same time, a large number of cracks appeared on the surface of the material, accompanied by skin shedding, and the surface decomposition and carbonization phenomenon occurred. The decomposition of the -COOR group and -C=O group inside epoxy resin is accompanied by the generation of -OH and -COOH groups. The surface flashover characteristics of epoxy resin are positively correlated with the content of water molecules in the air, and the hydrophilic -OH and -COOH groups lead to the degradation of its electrical properties. The research results of this article can provide a reference for the operation and maintenance of switchgear with epoxy resin as the main insulation structure.