The process of resin rich insulating materials for use in high voltage rotating machines

During the past ten to fifteen years all manufacturers of rotating machines have been obliged to give consideration to changing from the traditional thermoplastic insulation systems to those based on thermosetting resins. The established systems have used shellac and/or bitumen with mica splittings as the main dielectric barrier, and more recently glass cloth as the supporting medium. The change contemplated has been to a thermosetting insulation system incorporating synthetic resins, with mica paper replacing the mical splittings and glass cloth remaining as the supporting fabric.