Difference in insulation characteristics and mechanism between AC and DC XLPE cable's material

In order to understand the difference between DC and AC cable materials in their insulation characteristics, we comparatively measured the space charge and electrical properties of DC and AC materials, and analyzed the reasons of causing the difference by some tests and FTIR. The results show that, compared with AC cable materials, DC cable material has better space charge distribution, smaller dispersion but slightly lower voltage of breakdown in DC fields, and less impurity ion conductance. FTIR results show that the amount of carboxide in DC cable materials is different from that of AC cable materials. Since the amount of carboxide is an index of the integrity of main chains and the concentration of polar groups, we find that the two are the main reason for the difference in electrical properties between DC and AC cable materials.