GB190525287A - Method of and Apparatus for Striking Electric Arcs between Electrodes. - Google Patents

Abstract

25,287. Petersson, A. J. Dec. 5. Electric furnaces; arc lamps.-In furnaces for treating gases, in arc lamps, or elsewhere, electric arcs are started between subsidiary pairs of electrodes, which are connected so as to take but little energy, and transferred to the main electrodes. Variation in the resistance of the main arcs is thus diminished. In one form of furnace, of which Fig. 1 is a vertical section, each of the subsidiary electrodes 1, 2 and main electrodes 3, 4, 5, 6 is connected to alternating-current mains through the primary of a transformer 7, 8, 9, 10, 11, 12, and is also in the circuit of the secondary of the transformer. An arc formed between the electrodes 1, 2 moves upwards until it meets the lower ends of the electrodes 3, 4, which ends are flattened or enlarged for this purpose. The arcs between the electrodes 1, 3 and 2, 4 continue until the resistance of the arc between the electrodes 3, 4 becomes so great that another arc is formed directly between the electrodes 1, 2. The arc between the electrodes 3, 4 is similarly transferred to the electrodes 5, 6. The movements of the arcs may be produced by means of an electromagnet E, Fig. o, having pole-pieces extending vertically on each side of the furnace. Both the electro-magnet and the arcs are supplied with direct currents, or with alternating currents of the same period ; if, however, the main electrodes 26, 27, &c., Fig. 10, are placed both above and below the subsidiary electrodes 18, 19, direct current may be used for the electro-magnet and alternating current for the arcs. The currents supplied to the different electrodes may in this case be of different phases. Inductances F are placed in circuit with the electrodes. In another modification, there is a central vertical electrode, around which are other electrodes forming an interrupted helix ; a curved arm projects from the central electrodes to within arcing distance of the lowest helical electrode, and the lower end of each of the other helical electrodes extends between the upper end of the next one below it and the central electrode.