What materials are commonly used in high voltage transformer bushings?

Common materials used in high voltage transformer bushings include porcelain, resin-impregnated paper (RIP), and resin-bonded paper (RBP) for insulation. Porcelain is typically used for outdoor bushings due to its durability and resistance to environmental factors. RIP bushings use paper impregnated with resin, providing high dielectric strength and moisture resistance. Some modern bushings use epoxy resin as insulation, which offers good mechanical strength and resistance to environmental stress. The oil or gas within the bushing also serves as an insulating and cooling medium.