Self-Healing in Metallized Film Capacitors: Theory of Breakdown Interruption

A theory of self-healing (SH) in metallized film capacitors is introduced. The interruption of the filamentary breakdown current in the thin dielectric insulation occurs when the thermally driven increase of the series impedance in the electrode metallization destabilizes the breakdown plasma arc. The interruption process can be described as a switching process which is self-induced by feed-back via Joule heating. The theory is illustrated with an electric arc-like model for the breakdown current, coupled to the two-dimensional temperature-dependent RC-transmission plane defined by the two metallization electrodes. A specific model realization is implemented in a multi-physics finite element method simulation tool (Comsol) and illustrated with a few results for electrodes with and without segmentation.