What insulation materials are used in high voltage transformer bushings?

Common insulation materials include porcelain, epoxy resin, and resin-impregnated paper (RIP). Porcelain is durable and has high mechanical strength, making it suitable for outdoor applications. RIP bushings use paper impregnated with resin, providing excellent electrical insulation. Epoxy resin is used for solid bushings, offering good electrical performance and resistance to moisture and environmental factors.