Investigation of Dielectric Properties and Structural Changes in XLPE Composite Insulation of Covered Conductor due to Thermal Aging

Investigating the dielectric characteristics and structural alterations in XLPE composites, commonly employed in the insulation of covered conductors, stands as a pivotal research focus. In this study, we examined the variation in dielectric loss (tanδ) concerning frequency and voltage, influenced by thermal aging in XLPE insulation. To achieve this, the samples underwent aging at 120°C for six periods, a total of 450 hours. Furthermore, we conducted PD tests, FTIR, and SEM assessments on the insulation both before and after the aging process. A comprehensive analysis of the material's property changes during thermal aging was performed by comparing the PD test results with the tanδ measurements. In order to delve deeper into the interpretation of these findings because of thermal aging, we explored both internal and surface structural modifications, which directly impact tanδ and PD values, utilizing FTIR and SEM techniques.