Parametric study of a two-stage high-power DC circuit breaker is carried out. It is a current-limiting breaker which is characterized by a fast opening time. The circuit breaker under consideration consists of two vacuum interrupters in series and one of them has the semiconductors in parallel. The principle of operation of this vacuum interrupter is mainly based on providing an alternate path for the load current to flow through parallel-connected diodes so that the contacts of the vacuum interrupter can be opened under minimal arc conditions. The diodes help restore the dielectric strength of the second vacuum interrupter when the counter pulse capacitor switches the current from the diodes and the second vacuum interrupter to the capacitance and varistor. A fast circuit breaker substantially reduces the short circuit current. This is especially important for the circuits with small inductances and therefore high current derivatives.