Research on the Influence of the Internal Resistance of the Film Capacitor on the Characteristics of the Repulsion Mechanism

The short-circuit breaking function of a DC circuit breaker is realized by a repulsion mechanism driven by a customized MKMJ2-200 film capacitor. In order to ensure the reliable operation of the rapid repulsion mechanism, it is necessary to conduct in-depth research on its action characteristics. In this paper, a mathematical model is established around the design index of the repulsion mechanism; the results of voltage, current, electromagnetic repulsion, and the displacement of the repulsion plate are simulated and analyzed. Focusing on the problem that the excessive internal resistance RC of the film capacitor may cause the breaking failure, the simulation and analysis of the influence of the RC change on the characteristics of the repulsion mechanism; the calculation method combining simulation and actual measurement is used to quantitatively analyze the composition of the RC, and the RC is formulated <20mΩ design index. The results show that, under the harsh conditions of the capacitor volume limit in this case, the metal plating resistance and the sprayed gold layer resistance each account for about 50% of the internal resistance RC of the capacitor.