Multiphysics Arc Simulation of a Miniature Circuit Breaker for Prediction of Short Circuit Interruption Performance

Miniature circuit breakers (MCB) are electro-mechanical switching devices used in residential and industrial applications to provide protection against overload conditions and short circuit (SC) fault events. With these devices, arc dynamics during SC event determines the achievable interruption performance. Therefore, modeling of arcing processes is performed to better understand the arc behavior, which is difficult to observe in testing. A coupled magneto-hydrodynamics model is developed, including the effects of outgassing from ablative plates and arc splitting by metal plates. The required inputs for the coupled arc simulation - such as force on the contact carrier, contact dynamics, and resistivity of the components - are obtained by state-of-the-art electromagnetics, multibody-dynamics (MBD), and thermal simulations. The effect of device internal gas recirculation is investigated in detail and results show the influence on arc motion and restrike probability. Finally, model results for 6 kA and 10 kA SC load cases are compared with experimental results. Predicted arc voltage and let-through energy are consistent with measurement results.