Power supply system for a direct-current drive, comprising • a power converter for at least one direction-dependent two-quadrant operating mode, • at least one associated pulse-based actuation device (28, 30), • an input-side connection for connecting the power converter to a power supply grid, • and an output-side connection for connecting the power converter to a direct-current drive, • at least one mechanical interruption device (38, 40) for the input-side connection and/or the output-side connection, • wherein the power supply system is provided to continually provide values of a current flowing on the output side during operation, wherein the power supply system performs the following steps: • receiving a safe torque off signal, • in the event of receiving a safe torque off signal, immediately adjusting the output voltage of the power converter such that the current flowing on the output side is brought down to zero or at least below a safety-critical limit value close to zero already within a first time interval, characterized in that • once the first time interval, which begins when the safe torque off signal is received, has elapsed, interrupting the output of pulses to the power converter and/or interrupting the output of a current-direction signal to the power converter, with the result that a feed of actuation power through the actuation device (28, 30) into the power converter is interrupted, • supplying an interruption signal to the at least one mechanical interruption device (38, 40) for precisely the case in which, once a second subsequent time interval has elapsed, the current flowing on the output side has not decayed below a safety-critical limit value. • a power converter for at least one direction-dependent two-quadrant operating mode, • at least one associated pulse-based actuation device (28, 30), • an input-side connection for connecting the power converter to a power supply grid, • and an output-side connection for connecting the power converter to a direct-current drive, • at least one mechanical interruption device (38, 40) for the input-side connection and/or the output-side connection, • wherein the power supply system is provided to continually provide values of a current flowing on the output side during operation, • receiving a safe torque off signal, • in the event of receiving a safe torque off signal, immediately adjusting the output voltage of the power converter such that the current flowing on the output side is brought down to zero or at least below a safety-critical limit value close to zero already within a first time interval, characterized in that • once the first time interval, which begins when the safe torque off signal is received, has elapsed, interrupting the output of pulses to the power converter and/or interrupting the output of a current-direction signal to the power converter, with the result that a feed of actuation power through the actuation device (28, 30) into the power converter is interrupted, • supplying an interruption signal to the at least one mechanical interruption device (38, 40) for precisely the case in which, once a second subsequent time interval has elapsed, the current flowing on the output side has not decayed below a safety-critical limit value.