Failure Mechanism of Metallized Polypropylene Film Capacitors Under Impulse Voltage: Al Aggregation on Metallization Layer Surface

ABSTRACT Metallized polypropylene film capacitors (PP‐MFCs) are critical in high‐voltage applications due to their self‐healing capability and stability. However, under extreme conditions (high voltage, elevated temperature, and impulse stress), PP‐MFCs experience dielectric breakdown and thermal aging for eventual failure. In this work, we investigate failure mechanisms in detail, revealing Al aggregation on the metallization layer. Structural, thermal, and electrical analyses confirm that nonuniform electric fields induce Al migration and aggregation, leading to severe field distortion, dielectric aging, and breakdown. To address this problem, an antistatic layer may be introduced between the polypropylene film and the metallization layer. The study provides novel theoretical insights into the aging and breakdown mechanisms of dielectric materials in PP‐MFCs under combined electric field and thermal stresses, which may be of great significance for developing high‐performance film capacitors in high‐voltage operations.