A power supply device is provided for metallurgical equipment, which is to be operated with electric energy with a non-linear load and has a maximum power consumption equal to or greater than 180 MVA, such as for an electric arc furnace having a power consumption equal to or greater than 180 MVA. In such a power supply device, at least two structurally equivalent three-phase furnace transformers (100, 200) having an output power rating equal to or greater than 90 MVA include a delta interconnection (D) on the input side thereof and an external interconnection (iii) on the output side thereof. A low voltage-side parallel circuit (400) of output-side low voltage connectors of the furnace transformers (100, 200) includes symmetrized external delta interconnections implemented as water-cooled high current conductors. The low voltage-side parallel circuit is connectable in an electrically symmetrized manner to electrodes of the metallurgical equipment (10).

A power supply device is provided for metallurgical equipment, which is to be operated with electric energy with a non-linear load and has a maximum power consumption equal to or greater than 180 MVA, such as for an electric arc furnace having a power consumption equal to or greater than 180 MVA. In such a power supply device, at least two structurally equivalent three-phase furnace transformers (100, 200) having an output power rating equal to or greater than 90 MVA include a delta interconnection (D) on the input side thereof and an external interconnection (iii) on the output side thereof. A low voltage-side parallel circuit (400) of output-side low voltage connectors of the furnace transformers (100, 200) includes symmetrized external delta interconnections implemented as water-cooled high current conductors. The low voltage-side parallel circuit is connectable in an electrically symmetrized manner to electrodes of the metallurgical equipment (10).

A power supply system for arc furnace is described. The power supply system includes a power converter and a polyphase transformer. The power supply system further includes first disconnecting means connecting the input of the power converter to the primary circuit, second disconnecting means connecting the output of the power converter to the primary circuit, and the power supply system further includes a control circuit configured to control the power converter to supply the electrode and to stabilize the courant and the voltage delivered by the grid to reduce reactions in the grid when the first disconnecting means are open and the second disconnecting means are closed, and to control the power converter to stabilize the courant and the voltage delivered by the grid to reduce reactions in the grid when the first disconnecting means are closed and the second disconnecting means are open.

A power supply system for arc furnace is described. The power supply system includes a power converter intended to be connected to a polyphase supply grid and a polyphase transformer comprising a primary circuit connected to the power converter and a secondary circuit intended to be connected to at least one electrode of the arc furnace. The power converter includes an input device, a link circuit that has a first bus and a second bus, and an output device. The power supply system further includes a command circuit configured to command the input device and the output device to supply the electrode and to stabilize the courant and the voltage delivered by the grid when the electrode of the arc furnace is supplied by the power supply system to reduce rejections in the grid.

A melting plant includes an electric furnace, provided with one or more electrodes and chemical substance introduction devices, and a management apparatus including a decoupling unit disposed between an electricity grid and the electric furnace. A method for managing the melting plant is also disclosed.

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 Formula (I); and, a ballast inductor having an inductance L; characterized in that inductance L is such that Formula (II) and Formula (III). 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.

[00001]$\begin{array}{cc};& \left(I\right)\\ L>\left(\frac{U_0}{1500}\right).Math.,& \left(\mathrm{II}\right)\\ L<\frac{1}{f_s}.Math.\left(\frac{U_0}{200}\right).& \left(\mathrm{III}\right)\end{array}$

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 Formula (I); and, a ballast inductor having an inductance L; characterized in that inductance L is such that Formula (II) and Formula (III). 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.

[00001]$\begin{array}{cc};& \left(I\right)\\ L>\left(\frac{U_0}{1500}\right).Math.,& \left(\mathrm{II}\right)\\ L<\frac{1}{f_s}.Math.\left(\frac{U_0}{200}\right).& \left(\mathrm{III}\right)\end{array}$

At least one measurement value of a measurement variable characterizing the operating state of each of a plurality of system components that influence the operating conditions of an arc furnace is detected and compared to a respective currently permissible threshold value for the measurement variable. A maximum power that can be supplied to the arc furnace within a time window while satisfying all currently permissible threshold values is determined based on the result of the comparison.

The present invention relates to a melting equipment including: two direct-current arc furnaces each including two or more graphite electrodes; a power supply unit including four or more power supply devices; a connection switching unit configured to selectively connect each of the power supply devices to each of the direct-current arc furnaces; and a power supply control unit configured to control power supply from each of the power supply devices to each of the direct-current arc furnaces, in which power supply to only any one of the two direct-current arc furnaces and simultaneous power supply to both direct-current arc furnaces are selectable, and during the simultaneous power supply, power is supplied exceeding 50% of capacities of all the power supply devices to any one of the direct-current arc furnaces.

The present invention relates to a melting equipment including: two direct-current arc furnaces each including two or more graphite electrodes; a power supply unit including four or more power supply devices; a connection switching unit configured to selectively connect each of the power supply devices to each of the direct-current arc furnaces; and a power supply control unit configured to control power supply from each of the power supply devices to each of the direct-current arc furnaces, in which power supply to only any one of the two direct-current arc furnaces and simultaneous power supply to both direct-current arc furnaces are selectable, and during the simultaneous power supply, power is supplied exceeding 50% of capacities of all the power supply devices to any one of the direct-current arc furnaces.