Multiphysics Modeling of Contact Dynamics in Circuit Breakers

The contact dynamics in a low-voltage circuit breaker contact assembly have been modeled using a multiphysics approach. The approach considered the effects of current constriction and Lorentz forces acting to separate the contacts, while incorporating the presence of the arc established between the open contacts in providing a path for continued current flow. Contact movement, due to these forces as well as additional tripping mechanism action, was determined. The results compare well with high-speed x-ray video images captured during an actual short circuit test.