New Class F Vacuum-Pressure impregnation insulating materials

New epoxy resin based Vacuum-Pressure impregnation materials have been developed. Thermal aging tests of the 74021 solventless, low viscosity resin and the 77953 micaceous insulation indicate 155°C (Class F) capability. Chemical and gamma radiation resistance of the cured materials are that expected of thermally stable, high heat distortion temperature epoxy resins. Dissipation factor values of the components as well as the combination are very low and give promise of operation at voltage stress levels typical of 13.8 KV apparatus. Voltage endurance tests on aluminum bar samples are in progress and will be reported later.