Simulation Research on Outer Sheath Defects of 110kV XLPE Based on Multiple Characteristic Quantities

The outer sheath serves as the primary line of defense for cables against external environmental corrosion, its structural defects have been confirmed as one of the key factors contributing to the aging of cable insulation and operational failures. To study the impact of different types of outer sheath defects on the cable's operating condition, this study selects three typical defects, mechanical damage, chemical corrosion, and indentation deformation as the research objects. By combining the actual structural parameters and material properties of the cable, a three dimensional finite element model is constructed, and a bidirectional coupled simulation of electromagnetic, thermal, and mechanical multi-physics fields is conducted to quantitatively analyze the effect of each defect on the internal temperature field and electric field distribution of the cable under different operating conditions. The simulation results indicate that: mechanical damage most easily leads to obstruction of axial heat flow conduction in the cable, resulting in significant heat accumulation; chemical corrosion weakens the heat dissipation capability of the outer sheath, causing an overall temperature rise; and indentation defects induce electric field concentration in localized areas, potentially triggering breakdown risks.