A control system for a vacuum arc remelting (VAR) process for a metal includes a direct current (DC) power source, a ram drive, voltage drip short sensor, and a controller, which includes a processor. The drip short sensor may be configured to measure a drip short frequency of the electric arc over a period of time. The controller is configured to determine a real time arc gap length between the electrode tip and the melt pool based on a correlation between the drip short frequency and arc gap length. The controller is further configured to control power input to the electrode by the DC power supply by determining an input power level to input to the electrode based on the real time arc gap length, the input power level configured to generate a desired arc gap length, by the DC power supply, at the input power level.

A method and an arrangement measures electrode paste in an electrode column of an electric arc furnace. The electrode column has a steel casing, is provided with a contact shoe ring, and is filled with electrode paste introduced from above and evolving from raw paste in the upper part of the steel casing to melted paste and to baked paste in the lower part of the electrode column. The level of the raw paste is determined with a laser beam transmitted by a first laser device. The level of the molten paste is determined with a laser beam transmitted by a second laser device. The data received from the laser devices is used for calculation of the distances of the levels of the raw paste and molten paste from the contact shoe ring.

A method and an arrangement measures electrode paste in an electrode column of an electric arc furnace. The electrode column has a steel casing, is provided with a contact shoe ring, and is filled with electrode paste introduced from above and evolving from raw paste in the upper part of the steel casing to melted paste and to baked paste in the lower part of the electrode column. The level of the raw paste is determined with a laser beam transmitted by a first laser device. The level of the molten paste is determined with a laser beam transmitted by a second laser device. The data received from the laser devices is used for calculation of the distances of the levels of the raw paste and molten paste from the contact shoe ring.

The method for adjusting the impedance of one or more phases of a secondary circuit of an electric furnace, in order to limit the unbalance between the phases themselves comprises the transformer (31), a variable impedance secondary circuit for one or more phases (F1, F2, F3), the rigid and fixed interconnection (32) for each phase (F1, F2, F3) connected to the transformer, the flexible cables (33) connected by means of the proximal end to the fixed interconnection (32), the electrode holding arms (34) connected to the distal end of the flexible cables (33), the conductive electrodes (35) fixed to the respective electrode holding arms (34). The rigid and fixed interconnection (32) of a phase (F1, F2, F3) comprises at least one turn (11), wherein the impedance is either continuously or discreetly variable in order to obtain the desired impedance value.

The method for adjusting the impedance of one or more phases of a secondary circuit of an electric furnace, in order to limit the unbalance between the phases themselves comprises the transformer (31), a variable impedance secondary circuit for one or more phases (F1, F2, F3), the rigid and fixed interconnection (32) for each phase (F1, F2, F3) connected to the transformer, the flexible cables (33) connected by means of the proximal end to the fixed interconnection (32), the electrode holding arms (34) connected to the distal end of the flexible cables (33), the conductive electrodes (35) fixed to the respective electrode holding arms (34). The rigid and fixed interconnection (32) of a phase (F1, F2, F3) comprises at least one turn (11), wherein the impedance is either continuously or discreetly variable in order to obtain the desired impedance value.

The invention relates to an electric arc furnace and a method for operating same. The electric arc furnace comprises a lower vessel and a lid 120 placed on said lower vessel. The lower vessel has a tapping device for tapping molten metal. At least one electrode protrudes through the lid into the interior of the electric arc furnace, said electrode being held by an electrode holding device. A supply voltage device 150 is provided for supplying an electric direct current or alternating current to the electrode 130. The aim of the invention is to allow a continuous operation of the electric arc furnace. This is achieved in that the electrode holding device has an electrode adjusting device for adjusting the electrode dependent on the wear of the electrode and an electrode nippling device for nippling the electrode during the operation of the electric arc furnace. According to the invention, both the electrode adjusting device as well s the electrode nippling device 144 operate when the supply voltage of the electrode is switched on.

The invention relates to an electric arc furnace and a method for operating same. The electric arc furnace comprises a lower vessel and a lid 120 placed on said lower vessel. The lower vessel has a tapping device for tapping molten metal. At least one electrode protrudes through the lid into the interior of the electric arc furnace, said electrode being held by an electrode holding device. A supply voltage device 150 is provided for supplying an electric direct current or alternating current to the electrode 130. The aim of the invention is to allow a continuous operation of the electric arc furnace. This is achieved in that the electrode holding device has an electrode adjusting device for adjusting the electrode dependent on the wear of the electrode and an electrode nippling device for nippling the electrode during the operation of the electric arc furnace. According to the invention, both the electrode adjusting device as well s the electrode nippling device 144 operate when the supply voltage of the electrode is switched on.

An electrode slipping device comprises an upper holder and a lower holder, both holders containing one or more clamping shoes and one or more clamping cylinders in co-operation with the clamping shoes. The clamping shoes are operable between a position where the electrode is clamped and a position where the electrode is unclamped. The clamping cylinder is connected to the electrode holder by first fastening means and to the clamping shoe by second fastening means such that the clamping cylinder can be released from engagement with the holder by unlocking both sets of fastening means.

An electrode slipping device comprises an upper holder and a lower holder, both holders containing one or more clamping shoes and one or more clamping cylinders in co-operation with the clamping shoes. The clamping shoes are operable between a position where the electrode is clamped and a position where the electrode is unclamped. The clamping cylinder is connected to the electrode holder by first fastening means and to the clamping shoe by second fastening means such that the clamping cylinder can be released from engagement with the holder by unlocking both sets of fastening means.

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.