Criteria for laboratory evaluation of encapsulating and impregnating resins used in electric motors

Because of their outstanding performance, numerous new encapsulation and impregnating resins and new methods for applying these resins have been introduced in the past 10 years. These new materials and processes have rapidly replaced conventional varnishes and conventional varnish impregnation processes in many instances. Their swift success has focused attention on defining the exact functional role or service duty required of each component of an insulation system. Recent re-rates of designs, and the desire to operate at higher and higher temperatures, have thus brought the industry face-to-face with the need for quick, economical, and reliable criteria for classifying the service potential of new resins and processes.