Thermal Aging Effects on Twisted Pair Capacitance and Partial Discharge Activity

Electrical insulation is a fundamental component in electric machines. Its performance is significantly influenced by operating conditions that induce aging. This study investigates the impact of prolonged thermal exposure on the dielectric properties of enamel insulation, specifically focusing on changes in capacitance over time. Experimental results indicate that while elevated temperatures accelerate the degradation of the insulation material, they do not result in a significant variation in capacitance. Among the three types of enamel considered, only one exhibited a noticeable change in capacitance within the first one hundred hours of testing, and this was observed solely at the intermediate test temperature during the aging test campaigns.