A brief history of development in electrical insulation

The history of electrical insulation from its origins to the present is briefly reviewed. In the 1800s the development of electrical apparatus made necessary the use of a variety of insulating materials to meet increasingly demanding needs. Up to about 1925 only naturally occurring products such as asphalt, rubber, mica, and cotton thread or fabric were generally used. When a plethora of synthetic insulating materials became available, both their use and the means for evaluating them became complex. Attention is given to examples of failures, with reference to cryogenics. sodium conductors, URD polyethylene cable, outdoor plastic insulators, and generator stator insulation