Studies on Thermal, Mechanical, and Morphological Properties of Aged XLPE Cables

The cross-linked polyethylene (XLPE) cable plays a crucial role as an insulating material in power transmission and distribution systems. Considering the adverse effects of aging on reliability and lifespan, the present study investigates the thermal, mechanical, and surface morphological characteristics of high-voltage XLPE power cables that have been exposed to chemical and hydrothermal aging. The mechanical properties of the specimens under consideration were evaluated and analyzed using impact strength experiments. It is found that, at room temperature, with XLPE specimen treated from unaged to chemical aging, the impact strength decreases from 233.3 kJ m−2 to about 192.31 kJ m−2, and the elongation at break decreases from 187.74% to about 114.06%. When performing the impact test with hydrothermal aging, the impact strength and the elongation at break further reduce to 71.43 kJ m−2 and 100.2%, respectively. Surface profiles of unaged and aged materials are studied using atomic force microscopy and surface roughness is calculated consequently. The formation of pits on the surface of aged samples was visible in the AFM images. AFM analysis revealed a significant difference in the pattern of the average surface roughness and topography of XLPE insulation aged in chemical and those aged in hydrothermal. It will be demonstrated that a decrease in contact angle is related to increased specimen weight and surface roughness. For the specimens studied, the experimental results revealed an inverse relationship between surface roughness and contact angle. The thermal stability of aged specimens was further tested and analyzed to compare them with their unaged counterparts. XLPE materials were examined qualitatively for their applicability as an effective insulating material in the high-voltage insulation environment.