Abstract: An electric arc furnace includes at least one electrode projecting into a furnace vessel for containing a charge to be heated and electrode support structure for moving the electrode in a direction along a path towards and away from the charge. An improvement to the electric arc furnace comprises a sensor for detecting the position of the electrode support structure from an initial position. A processor calculates one of a support structure travel distance from the initial position and a rate of electrode consumption. An alarm signal is generated in response to at least one of the travel distance and the rate of electrode consumption being at least equal to a respective predetermined threshold travel distance or a predetermined threshold rate of electrode consumption, either of which is indicative of an excess electrode consumption condition for a given heat.

Abstract: Method and device to control the force applied to the electrode-bearing arms of an electric arc furnace, the vertical regulation of the electrodes being achieved with an electrohydraulic or electropneumatic system consisting of an operational cylinder actuated by a fluid under pressure so as to raise and lower the electrodes, the control means of the system being adjustable by means of an electrical device, whereby the working pressure of the operational cylinder is measured by a pressure transducer (15) and is processed by a processor system (16) so as to obtain the weight of the electrodes and the condition of static pressure, the processor system (16) governing a quick-response servovalve (18) and being governed by an interface (19) of the system that adjusts the electrical current fed to the electrodes (11).

Abstract: A feedback control system for the impedance control of an electric arc furnace having at least one electrode, a hydraulic electrode actuator for adjusting the electrode. The actuator is adapted to be supplied with hydraulic fluid through a control valve. The furnace further includes a controller, which is connected to the valve actuator for the control valve, and impedance signal generator for delivering impedance signals to one input of the controller and a setpoint signal generator for delivering a setpoint signal representing a desired impedance to another input of the controller.

Abstract: Method to feed a three-phase direct-arc electric furnace with controlled current and also a three-phase electric furnace thus fed for the smelting of metals, e.g.

Abstract: An improved arc furnace regulator employs neural circuits connected in a multi-layer network configuration with various weighted relationships between the successive layers which are automatically changed over time as a function of an error signal by means of the back-propagation method so that the regulator gradually improves its control algorithm as a result of accumulated experience. The network is implemented in software which can be developed and run on a PC with extra co-computing capability for greater execution speed. A second trainable neural network which emulates the arc furnace is used to develop the error signal, and is trained in mutually exclusive time periods with the training of the regular network.

Abstract: This invention is directed to a smelting plant with shaft-like charging material preheater. In a smelting plant with an electric arc furnace (1) and a charging material preheater (2) of shaft configuration arranged laterally on the furnace, the outer walls of the charging material preheater in the lower region thereof are formed by the vessel wall (5) of the furnace while in the region thereabove they are formed by the walls of a shaft which is fixed in a holding structure (27). By a horizontal relative movement between the furnace vessel (3) and the holding structure (27) together with the vessel cover (6), without being impeded by the shaft (10) charging material can be charged from a scrap basket directly into the furnace vessel or through the displaced shaft into different regions of the furnace vessel (3). Charging material can be retained in the shaft by means of a blocking member (51) therein, and heated up during the refining phase.

Abstract: System for controlling the positions of each of the three electrodes of a three phase electric furnace to maintain optimum real power delivered to the furnace in the event of electrode short circuiting or arc extinction due to scrap movement in the furnace. The system includes means for determining the magnitude of arc voltage and arc current and means to change the position of selected electrodes when either arc voltage or arc current is determined to be zero.

Abstract: A method of controlling the course over time of a target temperature of a molten metal in a ladle, for example, in which the required heating power is produced by at least one plasma torch. Determination is made of the variation with time of a target temperature, the mass of an outwardly flowing melt, and a specific heat value of the melt present in the ladle. From the foregoing values there is ascertained the course of a corresponding setting signal for obtaining the heating power necessary to obtain the desired temperature course. Simultaneously and continuously the actual temperature of the melt is measured. When the actual temperature of the melt deviates from its target temperature in excess of a predetermined tolerance, the setting signal for the heating power is changed by decreasing such setting when an actual temperature exceeds the target temperature, and increasing such setting when an actual temperature is less than the target temperature.

Abstract: Operation control system for an electrothermal furnace having one or more electrode and a transformer unit for each electrode for supplying heating current to its associated electrode. The or each transformer unit includes a main transformer having a primary winding for receiving current from a mains and two secondary windings, and an additional transformer connected to derive an adjustable voltage from one of the second secondary windings. The adjustable voltage and the voltage across the other secondary winding of the main transformer are combined to supply the heating current to the electrode. The control system includes a switch and a current control unit connected in the transformer unit for giving the additional voltage a selected polarity relative to the voltage across the other secondary winding of the main transformer and for controlling the magnitude of the additional voltage.

Abstract: The electrode of an electric arc melting furnace is adjusted in height by a hydraulic cylinder having an operating chamber which is connected via a servo valve to a hydraulic pressure source or, respectively, to a reservoir. The servo valve is actuated by a control signal which is produced by a comparison of the actual value of the electric arc current and a predetermined desired current value. Additionally, the pressure in the operating chamber of the cylinder is measured and supplied to the control circuit as a feedback value. An important advantage deriving from the present invention is the ability to provide a control of the electrode motion by virtue of the measured pressure even before the electric arc is ignited and to steadily hydraulically support the electrode under any condition of operation. Accordingly, uncontrolled motions of the electrode are prevented which motions might result in an increased danger of breakage, in overcurrents or short-circuits.

Abstract: Apparatus for positioning an arc furnace electrode which includes a verticle tubular electrode mast which is both horizontally and vertically movable. Inside the mast is a hydraulic cylinder which has a double-acting piston. When the mast is in its uppermost position it may be locked whereby hydraulic fluid is removed from above the piston. Fluid is then introduced below the piston to raise it and the piston rod to a level above the furnace platform such that the mast can be moved horizontally over the platform.

Abstract: An impedance controller is used for controlling electrode-to-bath spacing in an arc furnace. Measured quantities proportional to the electrode voltage and the electrode current are determined and an actual impedance value is formed from the measured values by means of a divider. The actual impedance value is compared with a predeterminable desired impedance value to derive a control signal. If in the event of a short circuit, the actual impedance value reaches a predetermined lower limit, a switching element sets into the controller a signal causing full drive, so that the electrodes are raised at maximum velocity. If the sum of the two measurement quantities becomes zero, the output of the controller is cut off.