Abstract: 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.

Abstract: 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.

Abstract: It is proposed herein to employ thyristor firing angles as a fast prediction of flicker in power supply for an electric arc furnace. It is further proposed to actively modify operating variables for the electric arc furnace to maintain the flicker below a predefined threshold. Aspects of the present application use the thyristor firing angles in combination with control ranges of variable reactance devices to predict the flicker severity level generated by the electric arc furnace with thyristor-controlled variable reactance devices. Based on the predicted flicker level, at least one operating variable of the electric arc furnace may be changed, if required, to maintain flicker to acceptable limit.

Abstract: The present invention relates to an electric arc furnace, containing a furnace shell, an electrode, a furnace shell moving mechanism that supports the furnace shell so as to be movable on an installation surface, and a first insulation that electrically insulates between the furnace shell and the furnace shell moving mechanism.

Abstract: A remote monitoring system and method for electricity demand of a fused magnesium furnace group. The system has a data acquisition device, a local PC, a cloud server and a remote PC. The data acquisition device has a voltage transformer, a current transformer, an active power transducer, a first slave computer, a plurality of multi-purpose electronic measuring instruments and a second slave computer. The method includes acquiring smelting current and smelting power of each fused magnesium furnace and electricity demand of the furnace group, controlling the switch off/on of each fused magnesium furnace according to the smelting current and the smelting power of each fused magnesium furnace and the electricity demand of the furnace group, sending basic monitoring data to the local PC, and achieving data exchange between the local PC and the remote PC through the Zookeeper technology.

Abstract: 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.

Abstract: In a method for operating an electric arc furnace operated with an alternating voltage, a structure-borne sound signal occurring on a wall of the electric arc furnace is detected, from which structure-borne sound signal a parameter characterizing the flicker properties of the electric arc furnace is calculated. At least one process variable of the electric arc furnace is controlled on the basis of the calculated parameter. An electric arc furnace operated according to the method is used in and for a melting plant.

Abstract: A method of detecting an open arc in a DC plasma arc furnace which is based on detecting a linear decrease in the log of the magnitude of the frequency spectrum of the voltage between the anode and cathode.

Abstract: A method and system automatically determines when an electrode add event occurs in an electric arc furnace having a plurality of electrode columns, each carried by an electrode positioning system. Data is received correlating to the harmonic distortion of the electrical current output to the plurality of electrode columns. Data is also received correlating to control pressures in the electrode positioning systems. Steady state control pressure data is captured when the harmonic distortion data indicates a steady state condition. An electrode add event is thereafter determined when a pressure spike is identified in the steady state control pressure data.

Abstract: A contact wear detector includes an electrical contact 100 having a base layer 110 composed of a first material and a contacting layer 120 composed of a second material, to electrically contact an opposing contact in the circuit. The base layer is capable of having portions exposed through worn areas 125 of the contacting layer. The first material of the base layer is configured to form an arc 210 between the portions of the base layer exposed through the worn areas and the opposing contact when the contacts separate. The arc thus formed emits light 212 having a characteristic optical spectrum of the first material. An optical detector 220 is proximate to the electrical contacts, to detect the characteristic optical spectrum of the light emitted by the arc between the portions of the base layer exposed through the worn areas and the opposing contact.

Abstract: 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.

Abstract: Disclosed is a control system for a melting process in an electric arc furnace for melting a metallic material. By means of the present disclosure it is possible to minimize desired process properties such as the melting time or the total power consumption of the melting process. The system includes a processing unit adapted for receiving or collecting measured data of at least one process variable, determining the current state of the process, performing an optimization of the melting process, determining a process input based on the result of the optimization, and controlling the melting process by means of the process input. A method is also presented herein.

Abstract: A power supply arrangement for supplying a square-wave current (I2) to a load connected to an output of the power supply arrangement, in particular a power supply arrangement in an arc furnace for generating an arc, including a transformer (TU) with at least two primary-site taps (1U1, 1U2) which form an input of the power supply arrangement, and with several secondary-side taps (2U1, 2U2, 2U3, 2UN), a bridge circuit (BU) with several first half bridges (11, 12, 13) which include converter valves (V11, V12, V13, V14, V15, V16) and which each have a first terminal (A11, A12, A13) of the bridge circuit, with a bridge section with a choke (L1), and with a second half bridge (20) which has converter valves (V17, V18) and a second terminal (A20) of the bridge circuit (BU), wherein each first terminal (A11, A12, A13) is connected to one of the secondary-side taps (2U1, 2U2, 2U3) of the transformer (TU), wherein the second terminal (A20) is connected to the output.

Abstract: In a method for operating an electric arc furnace operated with an alternating voltage, a structure-borne sound signal occurring on a wall of the electric arc furnace is detected, from which structure-borne sound signal a parameter characterizing the flicker properties of the electric arc furnace is calculated. At least one process variable of the electric arc furnace is controlled on the basis of the calculated parameter. An electric arc furnace operated according to the method is used in and for a melting plant.

Abstract: An arrangement and method for load compensation in an electrical power network includes at least one voltage stabilization apparatus and at least one load line including at least one load compensation apparatus, at least one load and at least one separation reactor. In the arrangement, the separation reactor is to be connected in series with the load compensation apparatus and the load line is to be connected in parallel with the voltage stabilization apparatus.

Abstract: A sensor system for monitoring and controlling the performance of the bottom electrode and the deflection of an electric arc in an electric steel making furnace includes an organized matrix of anode pins interspersed with refractory material and extending toward an electrically conductive plate secured to distal ends of the anode pins. A sensing device includes two temperature sensors at spaced apart locations along each of a distributed select group of anode pins for providing corresponding electrical signals and a current sensor responsive to electrical current flowing through the anode pins of the distributed select group of anode pins for providing a corresponding electrical signal. A controller responsive to the electrical signals derived at the anode pins of the select group operates the power supply and a display for monitoring the electrical performance of the elongated anode pins for heating by the electric arc in the furnace.

Abstract: A sensor system for monitoring and controlling the performance of the bottom electrode and the deflection of an electric arc in an electric steel making furnace includes an organized matrix of anode pins interspersed with refractory material and extending toward an electrically conductive plate secured to distal ends of the anode pins. A sensing device includes two temperature sensors at spaced apart locations along each of a distributed select group of anode pins for providing corresponding electrical signals and a current sensor responsive to electrical current flowing through the anode pins of the distributed select group of anode pins for providing a corresponding electrical signal. A controller responsive to the electrical signals derived at the anode pins of the select group operates the power supply and a display for monitoring the electrical performance of the elongated anode pins for heating by the electric arc in the furnace.

Abstract: A sensor system for monitoring and controlling the performance of the bottom electrode and the deflection of an electric arc in an electric steel making furnace includes an organized matrix of anode pins interspersed with refractory material and extending toward an electrically conductive plate secured to distal ends of the anode pins. A sensing device includes two temperature sensors at spaced apart locations along each of a distributed select group of anode pins for providing corresponding electrical signals and a current sensor responsive to electrical current flowing through the anode pins of the distributed select group of anode pins for providing a corresponding electrical signal. A controller responsive to the electrical signals derived at the anode pins of the select group operates the power supply and a display for monitoring the electrical performance of the elongated anode pins for heating by the electric arc in the furnace.

Abstract: The invention relates to an electronic circuit and a method for feeding power to at least one electrode of an alternating-current electric-arc furnace, particularly for melting metal. Known circuits of this type typically comprise a series connection with a transformer for providing a supply voltage for the electric-arc furnace from a power grid (1) and a AC power controller (8) connected between the transformer (6) and the electrode (11) for regulating the current through the electrode (11). According to the invention, a further development for such electronic circuits is proposed, which development has a simple design, is inexpensive and prevents overload of the AC power controller (8) even in operating modes of the electric-arc furnaces at high electrode currents. This further development provides to bypass the AC power controller with a bypass switch (9) that is opened or closed with the help of a controller as a function of the amount of current flowing through the electrode (11).

Abstract: A method for operating an arc furnace, an oscillation measurement device for an arc electrode, and a configuration for the arc furnace are described. Using simple measures for operating the arc furnace, it is possible to carry out, in a particularly safe and productive manner, an oscillation measurement on the at least one arc electrode. On the basis of which the operation of the configuration for the arc furnace can be controlled with regard to the mechanical and/or electrical operating parameters.

Abstract: In a method for determining the size and shape value (M) for a solid material (S), in particular scrap metal, in an arc furnace (1), an electrode flow fed to an electrode (3a, 3b, 3c) for forming an arc furnace (L) between the electrode (3a, 3b, 3c) and the solid (S) is measured (30) and from the measured electrode flow (I (t)), an effective measurement value of the electrode flow is determined (31) and from the measured electrode flow (I (t)) (32), a flow part associated with a frequency range of the measured electrode flow is determined (32), and a quotient of the flow part and an effective measurement value is formed as a measurement of the shape and size value of the flow (M). Thus, a method is provided that enables a property of a fusible element introduced into one of the arc furnaces to be determined.

Abstract: An arc furnace, a control and/or regulating device for an arc furnace, and a method for operating an arc furnace are provided, wherein an arc for melting metal is generated by at least one electrode, wherein an arc associated with the electrode(s) has a first radiation power based on preselected operating parameters, wherein the arc furnace is operated according to a predefined operating program based on an expected process sequence, wherein monitoring is performed to detect whether an undesirable deviation exists between the actual process sequence and the expected process sequence. Because a modified second radiation power is specified if a deviation is present, and a modified second set of operating parameters, e.g., impedance value(s), is determined based on the modified second radiation power, a method is provided that permits a minimal melting time while minimizing consumption of operating resources, e.g., with respect to arc furnace cooling.

Abstract: A method for controlling a melt process in an arc furnace and signal processing component, program code, and data medium for performing said method are provided. According to the method, sound signals or vibrations from the interior of the furnace container are captured by solid-borne sound sensors, from which characteristic values can be derived for the distribution of melting material, melt, and slag in the furnace fill. A characteristic value SM for thermal radiation impinging on the furnace wall of the container, a characteristic value M for the lumpiness of the melting material in the volume of furnace fill, and a characteristic value MM for the change to the portion of solid melting material contacting the furnace wall are generated in priority sequence. The energy distribution at the electrodes is changed by a control system analyzing the characteristic values in priority sequence, such that thermal load peaks are dampened or even completely prevented.

Abstract: A reactance ballast device (V), in particular for an arc furnace, has an induction coil (1) and a free-standing load stepping switch (2), with the load stepping switch (2) being designed to adjust the reactance of the induction coil (1) while on load. A transformer (T), in particular for an arc furnace (O), has an associated reactance ballast device (V) of the type mentioned initially. An arc furnace (O), in particular for steel smelting, is preceded by a transformer (T) such as this.

Abstract: A power supply arrangement for supplying a square-wave current (I2) to a load connected to an output of the power supply arrangement, in particular a power supply arrangement in an arc furnace for generating an arc, including a transformer (TU) with at least two primary-site taps (1U1, 1U2) which form an input of the power supply arrangement, and with several secondary-side taps (2U1, 2U2, 2U3, 2UN), a bridge circuit (BU) with several first half bridges (11, 12, 13) which include converter valves (V11, V12, V13, V14, V15, V16) and which each have a first terminal (A11, A12, A13) of the bridge circuit, with a bridge section with a choke (L1), and with a second half bridge (20) which has converter valves (V17, V18) and a second terminal (A20) of the bridge circuit (BU), wherein each first terminal (A11, A12, A13) is connected to one of the secondary-side taps (2U1, 2U2, 2U3) of the transformer (TU), wherein the second terminal (A20) is connected to the output.

Abstract: A system and method for monitoring the operating parameters of an electric arc furnace having a primary electrical circuit comprising a primary current transformer. The method includes monitoring the furnace's primary current transformer; collecting data therefrom; transmitting the collected data to a server having an operatively connected monitor; and displaying the collected data on the monitor in substantially real-time. The server also collects information about the performance of the furnace from a programmable logic computer and information entered manually by an operator at a furnace monitoring viewer system, which may also be displayed in substantially real-time on the monitor.

Abstract: In a power supply system for a three-phase arc furnace (1), comprising at least one furnace transformer (4), the furnace transformer (4) is connected on the secondary side to the three-phase arc furnace (1). On the primary side, the furnace transformer (4) is connected to a three-phase supply mains (3) through an indirect converter (5). The indirect converter (5) comprises at least one rectifier (6) on the mains side, at least one inverter (7) on the transformer side, and an intermediate circuit (8) between the rectifier (6) and the inverter (7). Each phase of the three-phase supply mains (3) is connected to the intermediate circuit (8) through two converter elements (11) of the rectifier (6) in each case. Each primary-side phase of the furnace transformer (4) is connected to the intermediate circuit (8) through two converter elements (12) of the inverter (7) in each case.

Abstract: A magnetic electron exciter includes a rotor adapted to be rotated within a preselected range of rotational speeds, and having a plurality of magnets mounted therein preselected distances from the rotational axis of the rotor. A plurality of coils are positioned adjacent to the rotor, whereby rotation of the rotor creates an electrical current in the coils. First and second electrodes are spaced apart a predetermined distance, and are electrically connected with the coils to create an arc between the electrodes when the rotor is rotated relative to the coils.

Abstract: A drive system for operation of a tap changer for voltage regulation of a transformer on load. An electric motor is connectible to a movable part of the tap changer for moving the movable part for carrying out a tap change operation. An electric converter connects an electric power supply to the electric motor. A control arrangement is adapted to control the electric converter for controlling the operation of the motor and by that of the tap changer.

Abstract: A sensor system for monitoring and controlling the performance of the bottom electrode and the deflection of an electric arc in an electric steel making furnace includes an organized matrix of anode pins interspersed with refractory material and extending toward an electrically conductive plate secured to distal ends of the anode pins. A sensing device includes two temperature sensors at spaced apart locations along each of a distributed select group of anode pins for providing corresponding electrical signals and a current sensor responsive to electrical current flowing through the anode pins of the distributed select group of anode pins for providing a corresponding electrical signal. A controller responsive to the electrical signals derived at the anode pins of the select group operates the power supply and a display for monitoring the electrical performance of the elongated anode pins for heating by the electric arc in the furnace.

Abstract: A device for controlling an arc furnace installation has an automatic controller (3) wherein a functional unit (6) for furnace control, a functional unit (7) for electrode control and a functional unit (8) for melting control are integrated in the controller (3).

Abstract: The invention relates to a method for operating a melt-metallurgic furnace (2), particularly an arc furnace, during the operation of which a number of operating parameters are maintained within predetermined thresholds, wherein for this purpose a control or regulating device (1) is utilized. In order to obtain greater efficiency of the furnace, the invention provides that the control or regulating device (1) has a conventional control or regulating device (9) and a fuzzy regulating device (10), which each feed their correcting variables to a mediator (11), wherein the mediator (11) calculates the actuating signal used according to a predetermined weighting factor (F) from the correcting variable coming from the conventional control or regulating device (9) and from the fuzzy regulating device (10). The invention further relates to a melt-metallurgic furnace, particularly an arc furnace.

Abstract: A control system for and method of controlling a vertical position of at least one electrode of an arc furnace, where the arc furnace comprises a furnace transformer having a primary, input side and a secondary, output side which is electrically connected to the at least one electrode, the control system comprising: at least one current-measuring device for measuring a current as drawn by the arc furnace; a voltage-measuring device for measuring a voltage as applied across the arc furnace; and a control unit for dynamically determining a setpoint for the vertical position of the at least one electrode based on the measured values of current and voltage, and providing an actuating output for driving a lifting arrangement to adjust the vertical position of the at least one electrode so as to follow the dynamically-determined setpoint.

Abstract: In a method for determining a state variable of an electric arc furnace, especially for determining the level of the foamed slag (15) in a furnace, the energy supplied to the furnace is determined with the aid of at least one electric sensor while solid-borne noise is measured in the form of oscillations on the furnace. The state variable is determined by a transfer function which is determined by evaluating the measured oscillations and evaluating measured data of the electric sensor. The state of the foamed slag level can thus be reliably recognized and be monitored over time. The foamed slag level is decisive for the effectiveness with which energy is fed into the furnace. Furthermore, losses caused by radiation are reduced by covering the arc with the foamed slag. The improved measuring method allows the foamed slag level to be automatically controlled or regulated in a reliable manner.

Abstract: In a method for regulating the melting process in an electric-arc furnace (1) which contains a furnace charge (4) containing the following temporally successive principal phases: melt, slag, solid, the proportion and temperature of at least the melt phase are calculated by a model (3). The model (3) embodied as a multispatial model for the different phases of the furnace charge (4), enables to include the physical effect according to which the temperature (TM) of the overheated melt decreases shortly before the complete dissolution of the remainder of the solid, in spite of the energy supply. Moreover, this effect is counteracted in that the electrical and/or chemical energy input is temporarily increased in a targeted manner. The modelling enables the real temperature profile (TM) of the melt to be represented, thus also improving the predictability of the tapping temperature. The number of temperature measurements required is, thus, reduced.

Abstract: A method for operating an electric-arc furnace with at least one electrode has one tapping method step. At the beginning of the tapping step, the energy supply to the at least one electrode (2) of the electric-arc furnace (1) is not stopped and the energy is still supplied to the at least one electrode (2) even during the tapping step. The step can begin before the traditional operating methods of an electric-arc furnace (1). This saves time, reduces the consumption of electrodes and energy, and also increases productivity. The desired energy content of the raw steel (8) is secured by the pre-calculation of the alteration of the energy content of the melt (4) during the tapping step and the danger of over-heating is compensated.

Abstract: The invention relates to an electronic circuit and a method for feeding power to at least one electrode of an alternating-current electric-arc furnace, particularly for melting metal. Known circuits of this type typically comprise a series connection with a transformer for providing a supply voltage for the electric-arc furnace from a power grid (1) and a AC power controller (8) connected between the transformer (6) and the electrode (11) for regulating the current through the electrode (11). According to the invention, a further development for such electronic circuits is proposed, which development has a simple design, is inexpensive and prevents overload of the AC power controller (8) even in operating modes of the electric-arc furnaces at high electrode currents. This further development provides to bypass the AC power controller with a bypass switch (9) that is opened or closed with the help of a controller as a function of the amount of current flowing through the electrode (11).

Abstract: A furnace's operating efficiency is improved by simultaneously monitoring various furnace operating parameters such that the monitored values may be collectively examined and correlated to determine if the furnace is sub optimally operating. In particular, the electrode current, hydraulic valve spool position, hydraulic fluid pressure, and electrode mast position of an electrical arc furnace are simultaneously monitored and correlated to determine if any unidentified sub optimal operating conditions are present. By improving the chances of detecting and correcting sub optimal operating conditions, the present invention improves the electrode consumption and overall efficiency of a furnace's operation.

Abstract: The described methods and systems may be applied to electric arc furnace installations. In this context, the method and system provide an electrode position controller coupled to the feed rate controller so as to predictively anticipate the introduction of new source material and lower the electrodes so as to prevent arc extinguishment while variable reactors are controlled to maintain predetermined power set-points. The electrode position controller may be used in place of, or in addition to, the variable reactance control system to take corrective action to address power and/or current changes or unbalances.

Abstract: A method and system for stabilizing energy consumption in multiple loads, or in single multi-phase loads. The method and system also compensates for unbalance in multi-phase loads. A central controller monitors variable reactances in the loads and identifies situations of power and/or current fluctuation and/or unbalance. It determines appropriate corrective action by the other loads/phases to compensate for the power and/or current change or unbalance due to the problematic load, and it issues control signals instructing variable reactor controllers associated with the other loads to adjust accordingly. The method and system may by applied to electric arc furnace installations. The system and method may be employed to maintain a predetermined level of unbalance in the system.

Abstract: A method and system for stabilizing energy consumption in multiple loads, or in single multi-phase loads. A central controller monitors variable reactances in the loads and identifies situations of power and/or current fluctuation and/or unbalance. The central controller determines appropriate corrective action by the other loads/phases to compensate for the power and/or current change or unbalance due to the problematic load, and it issues control signals instructing electrode position controllers associated with the other loads to adjust accordingly. The method and system may by applied to electric arc furnace installations. The electrode position controllers may be used in conjunction with variable reactance control systems to take corrective action to address power and/or current changes or unbalances. The variable reactors respond orders of magnitude faster than the electrode positioning system.

Abstract: The electrode arrangement uses vertically oriented electrodes with side wall contacts for an electrothermic smelting furnace for aluminum production. The side wall contacts are radially moveable into the furnace to compensate for wear on the contacts. The side wall contacts can be hollow to allow a slag forming charge to be fed to the furnace.

Abstract: Protection systems are described for electrical systems such as electrical arc furnaces. The protection systems may be designed and used to detect and clear faults that may occur within the electric arc furnace. For example, a pair of Rogowski coils may be used to detect current at their respective locations along a conductors, and output corresponding signals to a multi-function, differential relay having multiple voltage and current inputs. By comparing the signals from the Rogowski coils, the differential relay may determine whether a fault exists at some point along the conductors and between the pair of Rogowski coils. Further, the relay may then, in response to the fault, trip a circuit breaker or other network protection device, so that the fault may be corrected.

Abstract: To re-ignite efficiently an arc-furnace arc extending between an electrode and a material to be melt, a second energy supply is provided to maintain a plasma link between the electrode and the melting material when the arc-furnace arc is interrupted The electrode is supplied by a large current power supply including a large current conductor having a self inductance and being connected to the electrode. The second energy supply is an electrical power supply wherein a high frequency bypass impedance is provided in a supply path to the large current conductor at a distance from a capacitive circuit to allow a high frequency resonant circuit to be formed by the conductor section between the capacitive circuit and the bypass impedance without adversely affecting the large current power supply of the arc furnace.

Abstract: A new control method is used to regulate the reactive power consumption of an electric arc furnace. Active and reactive power values are used space vector variables and serve as control parameter of the power source, which consists of a furnace transformer with current controllers and a booster transformer. This method helps maintain constant reactive power consumption, reduce flicker at the point of common coupling and minimize the disturbances in the power system.

Abstract: A method of making steel in an electric arc furnace is provided. The method comprises the steps of measuring electrical current in at least two phases of electrical power supplied to electrodes in the furnace during a campaign, establishing a setpoint current level and an input time interval, and switching between modes of inputting exothermic energy into the steel melt when at least two phases have measured current levels below the setpoint for the input time interval.

Abstract: Variable shunt and series connected reactors are used in a complimentary combination in an electric arc furnace to provide improved flicker control. A power control system for an time-varying AC load, such as an electric arc furnace, connected to an AC power supply line includes a first variable reactance intermediate the power supply line and the load, and a second variable reactance connected in parallel with the power supply line. A control system is provided for (i) monitoring load current and adjusting the first variable reactance in response to changes in the monitored load current; and (ii) monitoring reactive power draw by the load and adjusting the second variable reactance in response to changes in the monitored reactive power draw. The first variable reactance and second variable reactance are each primarily used to mitigate flicker at different times during the load operation.

Abstract: A power control system for an AC electric arc furnace. The control system includes variable reactors located intermediate a furnace power supply and arc electrodes that are height adjustable. The control system monitors operating characteristics of the furnace that are indicative of the active power consumption of the furnace and adjusts the variable reactors and the electrode height so as to minimize variations in the active power consumption.

Abstract: The invention pertains to a process and to a device for supplying current to an electric-arc melting unit for melting and heating metal, especially steel, with a three-phase a.c. source, which sends the current via devices for producing direct current or alternating current to at least one electrode projecting into the vessel of the melting unit. The three-phase a.c. source (91) is followed by at least two power supply modules (41, 4n), connected in parallel, where each power supply module (41; 4n) has an uncontrolled three-phase bridge (51, 5n), a direct-current intermediate circuit (61, 6n), and a transistor unit (71, 7n) connected in series, and where, downline from the power supply modules (41, 4n) in the current flow direction, a common current-carrying line (31) leads to at least one electrode (21) of the melting unit (11) and away from at least one other electrode (22, 24).

Abstract: Disclosed is an electrode control system for an electric arc furnace having a furnace transformer. The electrode control system includes a current transformer for measuring operating current of the electrode and a voltage transformer for measuring operating voltage of the electrode. An active power transducer is connected to the current transformer and the voltage transformer for calculating active power of the electrode from the measured operating current and operating voltage as a first output signal. A reactive power transducer is connected to the current transformer and the voltage transformer for calculating the reactive power of the electrode from the measured operating current and operating voltage as a second output signal. A programmable control unit is connected to the active power transducer and the reactive transducer for receiving the first and second input signals.