Compatibility studies with mica bonds and solventless epoxy impregnants for form-wound stators

A new simplified "screening" method, using small copper tubes, has been developed for evaluating the compatibilities of mica wrappers with solventless epoxy vacuum pressure impregnating resins. The technique permits a detailed evaluation of the factors affecting the impregnation of mica wrappers and tapes with solventless resins. Resin (impregnant) retention and drainage characteristics, as well as the electrical compatibilities (as determined by elevated temperature power factor and void content measurements) of six solventless epoxy impregnants with various mica wrappers, have been evaluated using this technique.