Abstract: A circuit breaker device is for coupling a DC voltage branch to a positive and a negative conductor on a DC voltage bus. In an embodiment, the circuit breaker device includes a series circuit including a safety fuse and a unidirectional switch module. The switch module has a parallel circuit includes a controllable semiconductor switch element that is conductive in a first current direction and a diode that is conductive in the opposite current direction.

Abstract: A switching device is for coupling a DC voltage branch to a DC voltage bus. The switching device includes a series circuit including a first switching module and a second switching module. A first diode is connected in parallel with the first semiconductor switching element and a second diode is connected in parallel with the second semiconductor switching element. A third semiconductor switching element is connected in parallel with the series circuit. A control device is connected to the first and second semiconductor switching elements, to the bridging semiconductor switching element, to the voltage sensor and to the current sensor. The control device is configured to, upon a first threshold value of the voltage being undershot and current flowing in an exceptional case, switch the bridging semiconductor switching element to the conducting state in order to facilitate a current flow from the DC voltage branch to the DC voltage bus.