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.

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 melting method including a step of loading solid metal material into an electric furnace, a step of generating an electric arc between at least one electrode and the metal material, a step of perforating the metal material during which said electrode is moved through said metal material, a step of melting the solid metal material in order to obtain a molten material, a step of refining said molten material by adding reaction compounds. At least one of said steps includes regulating the electric parameters of the electric arc.

A melting method including a step of loading solid metal material into an electric furnace, a step of generating an electric arc between at least one electrode and the metal material, a step of perforating the metal material during which said electrode is moved through said metal material, a step of melting the solid metal material in order to obtain a molten material, a step of refining said molten material by adding reaction compounds. At least one of said steps includes regulating the electric parameters of the electric arc.

An electronic device, and a magnetic energy harvesting device and method of harvesting magnetic energy, for electric metallurgical furnaces and similar environments. The device comprises a conductor which is configured to become induced with electricity in response to a time-varying magnetic field. The field may be irregular, such as near a metallurgical furnace or a similar environment. The electronic device may be a transmitter in a metallurgical electric furnace. The transmitter may be connected to an environment sensor. The electronic device may be powered by the magnetic energy harvesting device. The magnetic energy harvesting device may a wire loop or a coil. The method comprises inductively harvesting energy from magnetic field fluctuations caused by a metallurgical furnace or a similar environment to wirelessly power the electronic device.

A control device for an arc furnace includes an arc furnace control module for controlling the arc furnace and a flicker module for determining a flicker value in a grid supplying the arc furnace, wherein the arc furnace control module is adapted for controlling the arc furnace based on the flicker value and wherein the arc furnace control module and the flicker module are integrated into one structural component.

A direct current smelting electric furnace includes a rectifying control circuit, a rectifying power supply device, a short network device, a multi-load layout device including multiple electrodes, and an electric furnace body. The rectifying power supply device includes at least two double-circuit direct current power supply packs. Four output terminals of each double-circuit direct current power supply pack are connected to three electrodes in the multi-load layout device by the short network device to constitute two current circuits by an electric furnace weld pool load. Each electrode in the multi-load layout device is connected to homo-polar output terminals of a three-phase negative semi-cycle rectifying output circuit and a three-phase positive semi-cycle rectifying output circuit, separately. The rectifying power supply device-includes multiple output current circuits. The number of output current circuits of the rectifying power supply device is the same as the number of electrodes in the multi-load layout device.

This invention concerns power supplies suitable for electric arc gas heaters such a plasma torches. It more particularly relates to the dimensioning of the inductor in the switched-mode DC to DC converter used for feeding the torch. The invention concerns in particular a DC power supply for driving a non-transferred electric arc gas heater, comprising: an AC to DC rectifier providing a potential U.sub.0; a DC to DC switching converter having a switching frequency f.sub.s; a current control loop having a latency ; and, a ballast inductor having an inductance L; characterized in that inductance L is such that

[00001]$L>\left(\frac{U_0}{1.Math.5.Math.0.Math.0}\right).Math.,\mathrm{and}.Math..Math.L<\frac{1}{f_s}.Math.\left(\frac{U_0}{2.Math.0.Math.0}\right).$

Such a design ensures the stability of the current control loop, while also ensuring a sufficient amount of current ripple to spread out the erosion zone on the electrodes of the torch.

This invention concerns power supplies suitable for electric arc gas heaters such a plasma torches. It more particularly relates to the dimensioning of the inductor in the switched-mode DC to DC converter used for feeding the torch. The invention concerns in particular a DC power supply for driving a non-transferred electric arc gas heater, comprising: an AC to DC rectifier providing a potential U.sub.0; a DC to DC switching converter having a switching frequency f.sub.s; a current control loop having a latency ; and, a ballast inductor having an inductance L; characterized in that inductance L is such that

[00001]$L>\left(\frac{U_0}{1.Math.5.Math.0.Math.0}\right).Math.,\mathrm{and}.Math..Math.L<\frac{1}{f_s}.Math.\left(\frac{U_0}{2.Math.0.Math.0}\right).$

Such a design ensures the stability of the current control loop, while also ensuring a sufficient amount of current ripple to spread out the erosion zone on the electrodes of the torch.