Good limitations of the current in a circuit using an electromechanical breaker suppose a very fast opening of the contacts. Due to the fact that the electrodynamic repulsive forces do not generate enough acceleration, an actuator has to be used to improve the breaker performances. Since a traditional reluctant magnetic device is too slow for the application concerned, a propeller based on the Thomson effect has been chosen. FLUX2D simulations make possible a good understanding of the propeller’s operation and thus the improvement of its design.