A device switches a direct current in a branch of a direct current voltage network node. The device contains a constant current path extending between two connection terminals, in which a mechanical switch is disposed. The device further has a switching current path bridging the constant current path and a power switching unit is disposed therein. The power switching unit has power semiconductor switches which can be switched on and off and configured to interrupt a short-circuit current in the event of a fault. The device contains a longitudinal voltage source for generating a counter-voltage in a loop formed by the constant current path and the switching current path. The device can be used economically over long periods of time to control the load flow on a network node. Accordingly, the longitudinal voltage source has a circuit for connecting and disconnecting the electrical power.