Ultra-Fast Electromechanical Switch in Enhanced Active Resonant DC Circuit Breakers

DC circuit breakers (DCCBs) are a timely research subject as DCCBs are needed to handle DC faults in DC grids. Current commutation is one of the key processes for the majority of the DCCB topologies proposed in the literature. Enhanced active resonant DCCBs are a relatively new concept using a discharging closing switch, for instance a triggered vacuum gap, as core component. Up until now, enhanced active resonant DCCBs used a load commutation switch to assist the commutation from the mechanical switch to the triggered vacuum gap. In principle, it is possible to operate without load commutation switch if the arc voltage of the mechanical switch is sufficiently high to commutate the current. This article studies the current commutation in an enhanced active resonant DCCB from an ultra-fast electromechanical switch with an opening speed up to 20 m/s to a triggered vacuum gap without the assistance of a load commutation switch experimentally. When the arc voltage of the ultra-fast electromechanical switch becomes sufficiently high, the triggered vacuum gap is triggered. The current commutates from the ultra-fast electromechanical switch to the triggered vacuum gap in a few tens of microseconds. Successful current commutation is observed for load current and fault current.