Investigation on Insulating Properties of Epoxy Resin Impregnated Paper Affected by Curing Agents and Accelerator Contents

The curing formula is vital to the performance of epoxy resin impregnated paper (RIP) material. This work explored the effect of curing agents and accelerator contents on the thermal and electrical properties of RIP material. It was found that the RIP material cured with 1-phr accelerator has the optimal glass transition temperature, electrical conductivity, dielectric loss, and dc breakdown strength compared with RIP material cured by 0.5-, 2-, and 3-phr accelerator. The RIP material cured with methylhexahydrophthalic anhydride (MEHHPA) has better thermal and insulating properties compared with the RIP material cured with methyltetrahydrophthalic anhydride (METHPA). The existence of the crepe paper amplifies the influence of accelerator and curing agent for the hydroxyl groups affecting the curing process as well as the chain segment arrangement. This study provides research support for the design of the curing formula for RIP insulation used in dc bushing.