The paper presents the principle of a dc high-force compact actuator for operating vacuum circuit breakers. By using properly placed Ne-Fe-B permanent magnets, the actuator we propose has the following advantages: it is able to perform a large number of mechanical operation cycles (at least one million) with high frequency rate and high holding force in closed position. Through reducing air gaps and leakage fluxes and the introduction of permanent magnets in the magnetic circuit, the proposed technical solution ensures low power consumption, compactness, reliability and reduced manufacturing cost. Such a linear actuator proves to be versatile finding application in operating valves remotely, robotic systems, packaging machines, electric switchgears, medical equipment, production machinery etc. Least but not last, it may find application in transportation industry ranging from rail to aircraft equipment. The working principle of the actuator is presented, followed by preliminary calculations and finite element simulations (static and dynamic) in FEMM package, incorporating specially designed LUA scripts. Finally, measurements performed on an actuator prototype are presented and discussed.

Keywords: Linear dc actuator, Ne-Fe-B permanent magnets, Vacuum circuit breakers (VCB), High actuating force, High holding force, Efficiency, Compactness, Reliability, Cost efficiency