Thermal Runaway Indicators of Metallized Polypropylene Film Capacitors

Metallized film capacitors are a common cause of electronic system failure. Since some of their failures can lead to serious accidents and severe damage to their surroundings, such as explosions or fires, their fail-safe should be ensured independently of their intern structure. The aim of this article is to investigate the runaway process leading to these catastrophic failures. Non-destructive accelerated aging tests to prevent unusual failures are carried out on 42 capacitors. Their key characteristics are measured periodically. Runaway indicators are found and analyzed. Based on the results, knowledge about the runaway process is deepened. Furthermore, a solution appears to avoid the catastrophic failures.