A configuration of switches added to a line control circuit allows for switching back and forth between a configuration featuring a series-connected thyristor switch and reactor and a configuration featuring a parallel-connected thyristor switch and reactor. Connecting the reactor in series with the thyristor switch allows a controlled high-impedance circuit configuration that is particularly well adapted for cold furnace start-ups and furnace idling. In this manner, there is reduced need for such equipment as extra startup transformers, alternate low-voltage power supply configurations and temporary specialty electrical apparatus for cold furnace start-ups.

A configuration of switches added to a line control circuit allows for switching back and forth between a configuration featuring a series-connected thyristor switch and reactor and a configuration featuring a parallel-connected thyristor switch and reactor. Connecting the reactor in series with the thyristor switch allows a controlled high-impedance circuit configuration that is particularly well adapted for cold furnace start-ups and furnace idling. In this manner, there is reduced need for such equipment as extra startup transformers, alternate low-voltage power supply configurations and temporary specialty electrical apparatus for cold furnace start-ups.

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 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 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.

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 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.

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.

There is provided an atmospheric pressure air microplasma system designed for random bit generation including a plurality of plasma electrodes, a power supply module supplying a DC voltage for igniting an arc discharge between the plurality of plasma electrodes, wherein the ignited arc discharge results in establishing and sustaining an arc current channel between the plurality of plasma electrodes, a current probe for measuring and collecting electric current time series data from the arc current channel, and a data acquisition board connected to the current probe for saving the collected electric current time series data, wherein binary sequences are generated from the electric current time series data. Further, the generated binary sequences are proven to pass all 15 tests of NIST Statistical Test Suite and thereby prove to qualify as random sequences.