Effect of Thermal Strike on the Insulation Performance of Polypropylene Cable Under Short-Circuit Faults

Polypropylene (PP) is gaining attention as an environmentally friendly power cable insulation material, potentially replacing cross-linked polyethylene (XLPE), due to its excellent dielectric properties and recyclability. As thermoplastic materials, the performance of PP is significantly affected by high temperature. While IEC standard specifies thermal requirements for XLPE cable during a short-circuit fault, studies on the insulating properties of PP under similar conditions are limited. Based on the limitation of current research, the article aims to investigate degradation pattern of insulating properties of PP insulation materials under thermal strike due to short-circuit failure. First, the temperature and stress distribution within the cable during a short circuit are analyzed using finite element simulation. Subsequently, changes in the dielectric performance of the insulation material before and after thermal strike are examined. The results indicate that the insulating performance of PP decreases after thermal strike. Tests on physicochemical properties reveal decreases in crystallinity, molecular weight, and crystal integrity, which are believed to be the main reasons for the observed decline in dielectric properties.