Direct current interruption with commercially available vacuum interrupters

Future development of electrical distribution and transmission technologies is driving the development of direct current (DC) circuit breakers (CB). The absence of a natural current zero, the required short interruption time and the absorption of energy during every switching process are some of the challenges for these breakers. One possible DC CB concept is to create an "artificial" current zero in a vacuum interrupter (VI) by application of a parallel connected LC circuit with pre-charged capacitor. It is important to find the optimal LC-circuit configuration to interrupt low and high currents by the same counter current impulse magnitude and shape. Investigations on the influence of characteristic frequency of the LC circuit, pre-charged capacitor voltage, arcing time and magnitude of the direct current to be interrupted were performed. Furthermore, steepness of the transient recovery voltage (TRV) depends on the LC circuit parameters and has an impact on the breaking capability. The promising results support a concept of a DC CB, either exclusively with VIs or in combination with other CB types or semiconductor elements.