1 research outputs found
Impact of surface discharge plasmas on performance of a metallized film capacitor
Surface breakdown discharges are one probable failure mechanism of metallized polymeric film
capacitors used in power systems, traction drives, and other technological applications. To assess
whether surface breakdown discharges may undergo considerable elongation on the electrode
surface to affect significantly capacitor performance, an equivalent electric circuit model is
developed for metallized polymer film capacitors under the thermal equilibrium condition. With the
aid of a surface field gradient mechanism, propagation of surface plasmas is studied and the
necessary condition for their possible elongation is obtained. Numerical examples of a metallized
film capacitor are used to demonstrate that surface breakdown plasmas and their elongation are
unlikely to affect capacitor performance in a significant fashion. Then the generic problem of plasma
propagation is restudied under thermally nonequilibrium conditions. Based on a heat conduction
formulation in the one-dimensional limit, a temperature gradient mechanism is proposed to explain
the possible elongation of breakdown plasmas on an electrode surface. Numerical examples are
again used to deduce that thermally nonequilibrium surface plasmas are unlikely to evolve into
catastrophic flashover arcs to fail film capacitors