Investigation of Thermal Aging Effects on Partial Discharge Activity and Dielectric Properties in Enameled Wire Insulation

This research investigates to elucidate the effects of thermal aging on the dielectric and electrical insulation characteristics of enameled wires deployed in high-temperature electrical machinery, including motors and transformers. The significance of electrical insulation is paramount for the prevention of short circuits and the maintenance of operational integrity amidst a confluence of electrical, thermal, chemical, environmental, and mechanical stresses. The research study focuses on the degradation of insulation materials resultant from thermal stress, with a particular focus on the variations in Partial Discharge Inception Voltage (PDIV), dissipation factor (tanδ), and insulation capacitance (IC). Thermal aging assessments were executed on diverse types of enameled wires subjected to varying temperature and electrical conditioning paradigms. The findings reveal that increased temperatures expedite the deterioration of insulation, leading to a marked decline in PDIV—a critical metric for assessing insulation viability. When the applied voltage transcends PDIV, both tanδ and IC exhibit an upward trend with respect to aging duration, whereas in scenarios where the voltage remains below PDIV, IC escalates proportionally with aging while tanδ predominantly remains invariant in the context of thermal aging. The investigation further examines the progression of partial discharge characteristics, encompassing discharge amplitude, repetition rate, and phase distribution, thereby offering nuanced insights into the mechanisms of degradation. The results corroborate that thermal stress modifies dielectric behavior and partial discharge patterns, thereby undermining insulation efficacy and longevity. By establishing correlations between PDIV trends and thermal aging, this study facilitates the assessment and selection of optimal insulation materials aimed at bolstering reliability. Moreover, the outcomes substantiate the formulation of predictive lifetime models and maintenance strategies, ultimately contributing to the design of more resilient and economically viable electrical machine.