Electromagnetic Actuators for Ultra-fast Air Switches to Increase Arc Voltage by Increasing Contact Speed

In this article, the previously known Thomson coil has been used as an actuator for open-close of a prototype power switch instead of a conventional spring mechanism that can be used in future vacuum circuit breakers, HVDC breakers and hybrid fault current limiters. Feasibility of increasing the opening speed to 80 m/s and its momentum control is discussed through finite element method simulations. Dynamics of Thomson drive is simulated, and speed dependencies to the frequency and stored energy are extracted in few diagrams to facilitate actuator tune-up to reach this considerable speed for a rather heavy disk. The contact speed in an experimental prototype switch is increased up to 22.5 m/s, and the dependencies of the arc voltage generated in ultra-fast air switches to the opening speed are investigated. Measured arc voltages and high-speed recordings of arc cores are presented. It is shown that by increasing the contact speed, the arc voltage rises rapidly. Thus, the number of required series arcs and the total resistance is reduced, so lower commutation time for higher fault currents are possible in hybrid FCLs or HVDC breakers.