Influence of Degassing Process on AC Breakdown Behavior of XLPE Insulation in Power Cable

The degassing process during the production of cross-linked polyethylene (XLPE) insulated cables leads to non-uniform changes in both the content of by-products and the aggregated structure within the insulation, significantly affecting the breakdown behavior of the insulation layers. This paper investigates the AC breakdown characteristics of the inner, middle, and outer layers of XLPE cable insulation at different degassing durations, with a focus on the impact of by-product content and crystalline morphology on the breakdown mechanism. The results show that degassing effectively reduces the number of polar small molecular by-products within the insulation and promotes further perfection of the crystalline structure, reducing the proportion of amorphous regions, and improving the internal electric field distortion of the insulation, thereby enhancing the breakdown field strength. This phenomenon is more pronounced in the outer layer of the insulation.