Solid-state aided airgap for dc circuit breakers

A direct current (DC) solid-state circuit breaker comprising:

• a power electronics section that includes a first solid-state switching component;
• an airgap section connected in series with the power electronics section to establish a main current path configured to deliver a load current to a load, the airgap section implementing an isolation switch connected in series with a fail-safe interruption circuit that includes a current commutation switch, a second solid-state switching component, and an overvoltage protection device connected in parallel with one another;
• a sensing and control circuit in signal communication with the power electronic section and the airgap section, the control circuit configured to detect one or both of a fault event and an opening command, and in response to detecting one or both of the fault event and the opening command performs a fail-safe operation that controls the isolation switch at a time period, and controls the current commutation switch and the second solid-state switching component at a delayed time period that occurs after controlling the isolation switch,
• wherein the fail-safe operation includes a plurality of switching sequences that delay complete interruption of the load current using the fail-safe interruption circuit until after initially delaying the load current using the isolation switch.