Selection of antioxidants for capacitor grade polypropylene film: Insights into electrical performance of the oil-film system.

This article focuses on the migration mechanism of antioxidants in oil-impregnated polypropylene (PP) film used as insulation in high voltage power capacitors and its impact on the electrical performance of the oil-film system. Through molecular dynamics simulations and experiments, the study introduces a migration coefficient (ηm) based on inter-molecular binding energies to quantify antioxidant migration tendencies between PP film and insulating oil. Results show that lamellar-structured antioxidants with ηm > 1, such as 1010 and 3114, tend to migrate into the oil, causing increased dielectric loss and reduced breakdown strength, while phosphite antioxidants containing phosphorus atoms can decrease the film's breakdown strength by facilitating charge migration. The research highlights the importance of selecting antioxidant types and combinations carefully to optimize the thermo-oxidative stability and electrical reliability of capacitor-grade PP films.