New electrical insulating mineral oils

Since World War I, electrical insulating oils for transformers and allied electrical equipment have been refined from naphthenic petroleum crude oil stocks. The resulting oils show little or no wax formation and have acceptable dielectric, mechanical and heat transfer properties at temperatures down to −40°C. Usable naphthenic crude oils are coming into short supply and there is a real possibility of a short-fall in supply of the traditional oils in the 1980's. This progress report describes selected portions of work done during the first third of a program directed toward evaluation of potential replacement liquids, particularly other mineral oils.