An electric arc furnace (EAF) including a raw material container, a set of electrodes, a set of electrical potential transformers, and a reference signal verification device. The set of electrodes are configured to be controllably extended toward the raw material container. The set of electrical potential transformers are correspondingly coupled to the set of electrodes. The reference signal verification device is configured to carry out the steps of reading a reference signal value coming from the raw material container; comparing the reference signal value to an approximated value; and determining that there is a loss of the reference signal if the reference signal value is not within a predetermined amount of the approximated value.

An electric arc furnace (EAF) including a raw material container, a set of electrodes, a set of electrical potential transformers, and a reference signal verification device. The set of electrodes are configured to be controllably extended toward the raw material container. The set of electrical potential transformers are correspondingly coupled to the set of electrodes. The reference signal verification device is configured to carry out the steps of reading a reference signal value coming from the raw material container; comparing the reference signal value to an approximated value; and determining that there is a loss of the reference signal if the reference signal value is not within a predetermined amount of the approximated value.

An electrode joining apparatus for joining a first electrode and a second electrode includes an electrode holder configured to receive the first electrode and a torque device positioned above the electrode holder. The torque device is configured to engage and rotate the second electrode relative to the first electrode. A lift is disposed on the apparatus to move the torque device relative to the electrode holder. In some embodiments, the lift includes a mechanism such as a powered actuator operable to raise the torque device above the electrode holder. In additional embodiments, the lift includes a carriage that is vertically moveable relative to the electrode holder, and the torque device is attached to the carriage.

An electrode joining apparatus for joining a free electrode to a fixed electrode. The electrode joining apparatus includes an electrode holder configured to selectively hold the fixed electrode and a torque device positioned above the electrode holder, the torque device configured to grip and spin the free electrode to join the electrodes. The electrode joining apparatus can include an axial passage defined through the electrode holder and the torque device. A retractable spacer can be movably connected to the electrode joining apparatus, the retractable spacer configured to selectively move into the axial passage. The retractable spacer can be used to form a gap between the free electrode and the fixed electrode before the joining process is initiated. Electrode joining apparatus can also include a spacer drive mechanism coupled to the retractable spacer, the spacer drive mechanism configured to selectively move the retractable spacer into the axial passage.

An electrode joining apparatus for joining a fixed electrode and a free electrode including an electrode holder configured to receive the fixed electrode and a torque device positioned above the electrode holder. The torque device is configured to grip and spin the free electrode to join the free electrode to the fixed electrode. A force sensor is coupled to the torque device. The torque device is configured to apply a force on the force sensor when the torque device engages the free electrode. The force sensor can detect a feedback force signal representative of the force applied by the torque device on the free electrode. The feedback force signal can be used to determine the torque applied to the free electrode by the torque device to help ensure that a proper joint is formed between the free electrode and the fixed electrode.

A vacuum arc remelting (VAR) system for forming an ingot from an electrode is disclosed. The system includes a crucible assembly configured to accommodate the electrode and the ingot. The system includes a primary electromagnetic energy source arranged about the crucible assembly. The primary electromagnetic energy source and the crucible assembly are configured to move relative to one another along a longitudinal axis of the crucible assembly. The system includes a secondary electromagnetic energy source arranged about an upper end portion of the crucible assembly. The secondary electromagnetic energy source is stationary and fixed to the upper end portion of the crucible assembly.

A vacuum arc remelting (VAR) system for forming an ingot from an electrode is disclosed. The system includes a crucible assembly configured to accommodate the electrode and the ingot. The system includes a primary electromagnetic energy source arranged about the crucible assembly. The primary electromagnetic energy source and the crucible assembly are configured to move relative to one another along a longitudinal axis of the crucible assembly. The system includes a secondary electromagnetic energy source arranged about an upper end portion of the crucible assembly. The secondary electromagnetic energy source is stationary and fixed to the upper end portion of the crucible assembly.

An electric power apparatus for an electric arc furnace comprises at least one electrode and is connectable to a power network to supply to the electrode the electric energy to generate an electric arc to melt a metal mass. The apparatus comprises an electric regulation unit interposed and connected to the power network and to the electrode and configured to regulate at least one electric quantity for powering the electrode. The apparatus comprises at least one detection device to detect the electric quantity, interposed between the electrode and the electric regulation unit, a positioning device to move the at least one electrode nearer to/away from the metal mass to be melted and a control and command unit.

An electric power apparatus for an electric arc furnace comprises at least one electrode and is connectable to a power network to supply to the electrode the electric energy to generate an electric arc to melt a metal mass. The apparatus comprises an electric regulation unit interposed and connected to the power network and to the electrode and configured to regulate at least one electric quantity for powering the electrode. The apparatus comprises at least one detection device to detect the electric quantity, interposed between the electrode and the electric regulation unit, a positioning device to move the at least one electrode nearer to/away from the metal mass to be melted and a control and command unit.

A method and a device for closed-loop control of an electrode gap in a vacuum arc furnace subjects an electrode gap of a melting electrode from the surface of a melt material to closed-loop control as a function of a droplet short-circuit rate. For this purpose, a histogram of detected droplet short-circuits is created on the basis of at least one droplet short-circuit criterion. The histogram is subdivided into sub-areas, a characteristic sub-area of the histogram is selected for closed-loop control purposes. The electrode gap is subjected to closed-loop control on the basis of the droplet short-circuits which can be associated with the selected sub-area.