Surface field dynamics in de film capacitors under an impulse voltage perturbation

For metalized polymer film capacitors, the dynamics of electric field on th e electrode surface and its resulting energy dissipation influence the onse t and scale of breakdown discharges within the capacitor unit, which in tur n is indicative of the reliability and lifetime. To gain an understanding o f the dependence of surface electric field on key system parameters, an equ ivalent circuit model is developed to simulate the temporal evolution of th e electric field distribution within a dc film capacitor subjected to an ex ternal impulse electric stress. A mosaic pattern of electrode segmentation is taken into account by means of an effective surface resistance and its e ffects on surface electric field and energy dissipation are computed numeri cally. Also considered are the effects of the number of electrode segments across a given length. In addition, electric energy dissipation is calculat ed to assess the level of possible temperature rise within the capacitor. B y addressing these two issues, it is shown that the numerical code develope d and its underlying methodology can serve as a complimentary tool to the p resent practice of capacitor designs and performance assessment.