GB1326091A - Electroslag refining of metals - Google Patents

Abstract

1326091 Electroslag refining apparatus ASSOCIATED ELECTRICAL INDUSTRIES Ltd 19 April 1971 [8 April 1970] 16741/70 Heading H5H [Also in Division G3] Electroslag apparatus comprises two consumable electrodes 2, 3 advanced in unison into the slag layer 5 and supplied by the secondary windings 9, 11 of respective transformers 7, 8 whose primary windings 13, 14 are connected to A.C. supply terminals 6, the voltages across the windings 9, 11 being variable in accordance with signals representative of the difference between the actual separation of each electrode from the molten metal pool 12 and a desired separation, so that the electrodes 2, 3 are consumed at the same rate. The actual separation signal is obtained by sensing the voltage and current between the electrode and the pool 12 to derive the impedance of the slag therebetween. The difference signals may control saturable reactors connected in the primary circuits of the transformers 7, 8. The movement of the electrodes is controlled by sensing the current through one of them or the current through both, in which case the sum or average of the two currents is the control parameter. The primary or secondary windings of the transformers 7, 8 are arranged so that the instantaneous currents 18, 19 through the electrodes 2, 3 are substantially equal and opposite, thereby reducing the inductances of the electrode circuits. The primary windings 13, 14 may be connected in series across the terminals 6, Fig. 5 (not shown) or across one phase of a three phase supply, Fig. 4 (not shown). Alternatively they may be connected to respective phases of a three phase supply, Fig. 3 (not shown) or to form a <SP>3</SP>/ 2 -phase Scott-connected arrangement therewith.