Aging Condition Assessment of XLPE Insulated Cables in Various Laying Environments Based on Isothermal Relaxation Current

The operating environments of cables are complicated, which directly affect the lifetime of cables. In order to explore the aging assessment of cables in various laying environments, the isothermal relaxation current (IRC) experiments were carried out on XLPE insulated cables aged in water and air. It shows that the trap density in insulation increases significantly due to the aging, and the effect of thermal aging on cable insulation in air is stronger than that in water Since the condition of the shield layer affects the cable, further tests of peeling force and resistivity of the shield layer were conducted to investigate the effect of different laying environments on the aging condition of the samples. Aging process reduces the peeling force, which may lead to the introduction of impurities or air gaps and accelerate the insulation distortion. Aging in air not only intensifies the aging of the insulation, but also has a serious impact on the semi-conductive layer.