Investigation on Regularities of Self-Healing Breakdown in Metallized Film Capacitors for AC Application

Abstract

Metallized film capacitors (MFCs) exhibit a distinctive self-healing capability, making them particularly suitable for reactive compensation in high-voltage power systems. However, frequent self-healing breakdowns or failures can significantly compromise capacitor lifespan and system stability. The underlying mechanisms governing self-healing behavior in AC applications remain insufficiently understood. This study establishes an experimental platform to systematically examine the influence of various factors on AC capacitor self-healing performance, while proposing design recommendations to minimize self-healing energy without compromising success rates. Key findings demonstrate that increased voltage leads to a dramatic expansion of self-healing area; elevated temperatures facilitate reduced self-healing energy but degrade insulation properties when excessive; thicker metallized films decrease power loss at the expense of substantially higher self-healing energy; and greater inter-layer pressure effectively diminishes self-healing energy. For optimal capacitor design, excessive field strength should be avoided; moderately increased operating temperatures enhance self-healing performance but must be balanced against thermal degradation risks; and film thickness selection requires careful consideration of both self-healing characteristics and thermal management. These findings offer valuable insights for the design optimization of AC capacitors in power system applications.