Abstract: An impedance controller is used for controlling electrode-to-bath spacing in an arc furnace. Measured quantities proportional to the electrode voltage and the electrode current are determined and an actual impedance value is formed from the measured values by means of a divider. The actual impedance value is compared with a predeterminable desired impedance value to derive a control signal. If in the event of a short circuit, the actual impedance value reaches a predetermined lower limit, a switching element sets into the controller a signal causing full drive, so that the electrodes are raised at maximum velocity. If the sum of the two measurement quantities becomes zero, the output of the controller is cut off.