Aging of Hermetic Motor Insulation

A different approach in thermal evaluation of hermetic insulation is presented. A random-wound bifilar coil of enameled wire, with or without varnish, is aged at a series of elevated temperatures while in a refrigerant atmosphere. Dielectric properties are measured repeatedly at each aging temperature and aging rates are calculated. From rate data at various aging temperatures, energies associated with the aging process are determined by the Arrhenius equation.