Abstract: In order to avoid damage to the inner walls of the arc furnace (1) and a reduction of the electric power when material (5) to be melted has been partly burned down in an arc furnace (1), additives (10) are fed to the filling opening of a hollow electrode (7) by means of a loose-material conveyor (25) during this critical melting phase. An arc (6) between the hollow electrode (7) and a melt (4) in the arc furnace (1) is thereby shortened. A loose-material container (9) is arranged at the end of the loose-material conveyor (25) at a distance from the electrode and can easily be separated from the hollow electrode (7) in order to permit the tilting of the arc furnace (1) to empty out the melt (4). Problematic waste materials which are to be disposed of, such as for example filter dust, can be added to the additives (10).

Abstract: In operation, DC arc furnaces generate undesired reactive load fluctuations which are compensated for by a power controller without special compensation reactance. In order to permit a melting operation of the arc furnace in weak AC systems the DC furnace is operated with at least two melting electrodes. A current controller is connected to each cathode via rectifiers. Each cathode is controlled with respect to its spacing from a melt by an electrode adjusting device and an electrode controller. Only one current controller one electrode controller are operationally connected, on an input side, to a power factor controller. Power factor control is thus performed with only one electrode assembly.