A plant for melting and/or heating metal material includes a furnace, electrical energy feed means and an electric power apparatus connected between the feed means and the furnace; and a corresponding method to power the melting and/or heating plant.

An electric power method for an electric arc furnace includes regulating the electric power frequency of a power voltage and a power current of the electrodes, independently from the mains frequency.

An electric power method for an electric arc furnace includes regulating the electric power frequency of a power voltage and a power current of the electrodes, independently from the mains frequency.

A power supply system for an electric arc furnace includes an AC input connectable to an electrical grid and an AC output for supplying at least one power electrode of the arc furnace; a resonant circuit interconnected between the AC input and the AC output. The resonant circuit includes a controllable bypass switch for connecting and disconnecting a circuit input and a circuit output of the resonant circuit and a capacitor and a main inductor connected in parallel with the bypass switch.

A power supply system for an electric arc furnace includes an AC input connectable to an electrical grid and an AC output for supplying at least one power electrode of the arc furnace; a resonant circuit interconnected between the AC input and the AC output. The resonant circuit includes a controllable bypass switch for connecting and disconnecting a circuit input and a circuit output of the resonant circuit and a capacitor and a main inductor connected in parallel with the bypass switch.

An electric power apparatus for an electric arc furnace comprises at least one electrode and is connectable to a power network to supply to the electrode the electric energy to generate an electric arc to melt a metal mass. The apparatus comprises an electric regulation unit interposed and connected to the power network and to the electrode and configured to regulate at least one electric quantity for powering the electrode. The apparatus comprises at least one detection device to detect the electric quantity, interposed between the electrode and the electric regulation unit, a positioning device to move the at least one electrode nearer to/away from the metal mass to be melted and a control and command unit.

An electric power apparatus for an electric arc furnace comprises at least one electrode and is connectable to a power network to supply to the electrode the electric energy to generate an electric arc to melt a metal mass. The apparatus comprises an electric regulation unit interposed and connected to the power network and to the electrode and configured to regulate at least one electric quantity for powering the electrode. The apparatus comprises at least one detection device to detect the electric quantity, interposed between the electrode and the electric regulation unit, a positioning device to move the at least one electrode nearer to/away from the metal mass to be melted and a control and command unit.

A metallurgical furnace including a vessel with a lower shell for containing a metal bath, the metal bath composed of molten metal and an overlying layer of slag. The lower shell is tiltingly supported and provided with a deslagging opening for evacuating the slag and a tapping opening for tapping the molten metal. The vessel includes an upper shell removably positioned on the lower shell and first and second inlet openings for feeding. The vessel includes a closing roof for the upper closing of the vessel removably positioned on the upper shell and a passage opening for the passage, through the same, of at least one electrode, at least one charge opening for feeding, through the same, charge material in the solid state. At least one of the inlet openings, passage opening, and charge opening is closed or associated with a closing element.

A metallurgical furnace including a vessel with a lower shell for containing a metal bath, the metal bath composed of molten metal and an overlying layer of slag. The lower shell is tiltingly supported and provided with a deslagging opening for evacuating the slag and a tapping opening for tapping the molten metal. The vessel includes an upper shell removably positioned on the lower shell and first and second inlet openings for feeding. The vessel includes a closing roof for the upper closing of the vessel removably positioned on the upper shell and a passage opening for the passage, through the same, of at least one electrode, at least one charge opening for feeding, through the same, charge material in the solid state. At least one of the inlet openings, passage opening, and charge opening is closed or associated with a closing element.

An electric arc furnace (1) operated with alternating current has a converter (2) which converts mains voltage (U), into primary voltage (U′) having a furnace frequency (f′). A furnace transformer (4) transforms the primary voltage (U′) into a secondary voltage (U″), supplied to electrodes (6) in a furnace vessel (8) (1). They apply electric arcs (10) to a melt material (9) in the vessel (8). The secondary voltage (U″) is also supplied to a capacitor assembly (7) on the output side of the furnace transformer (4) and the furnace transformer (4) is connected on the output side. A control device (5) controls the converter (2) such that a primary voltage (U′) output from the converter (2) to the furnace transformer (4) has a furnace frequency (f) of least ten times the mains frequency (f) and/or greater than 1 kHz.