The present disclosure relates to a DC generator that has at least one string, wherein the at least one string is formed by modules which are series-connected by a string line so as to generate a string voltage; and a switching device which is connected in series in the string line, in order to switch on and off the at least one string using the switching device. The switching device comprises a hybrid switch including a relay and a semiconductor switching device connected in parallel to the relay, wherein the semiconductor switching device includes at least one semiconductor switch. The switching device comprises a current sensor which is adapted to measure a negative current flow.