Effect of Accelerated Thermal Aging on Mechanical and Dielectric Properties of XLPE Cable Insulation

In this paper,accelerated thermal aging test on 10 kV XLPE cable insulation was carried in laboratory,in order to investigate the effect of accelerated thermal aging on mechanical and dielectric properties of XLPE cable insulation. We selected 100℃,140℃ and 160℃ as the aging temperature. The test results showed that thermal aging at low temperature benefited the crystallization of XLPE and the melting peak temperature of XLPE increased at this temperature. Thermal aging at relatively high temperature damaged the crystallization of XLPE,and the crystallization and melting peak temperature of XLPE decreased and the separated peaks occurred at this aging temperature. The mechanical properties of the material reduced during the thermal aging. At 100℃,the elongation at break decreased from 501. 92 % to 425. 25 %. At 140℃,the elongation at break decreased to 57. 58 %. At 160℃,the elongation at break decreased to 31. 95 %. The permittivity of unaged XLPE cable insulation was about 2. 4 in the range of the test frequency. The permittivity increased significantly after the thermal aging. Thermal aging accelerated the cleavage of the macromolecular chains and produced carbonyl groups and hydroxyl groups.