GB591016A - Devices allowing the measurement and adjustment of the resistance of an electrolysis cell - Google Patents

Abstract

591,016. Resistance measurements. COMPAGNIE DE PRODUITS CHIMIQUES ET ELECTROMETALLURGIQUES ALAIS, FROGES, ET CAMARGUE. April 9, 1945, No. 8762. Convention date, April 7, 1944. [Class 37] The resistance of an electrolytic cell is measured by measuring the ratio between a voltage proportional to the current through the cell and a voltage proportional to the voltage at the terminals of the cell reduced by a voltage equal to the E.M.F. of the cell. Alternatively, one voltage may be proportional to the voltage at the terminals of the cell and the other to the current through the cell increased by a constant term. As shown in Fig. 1, one coil 1 of a crossed-coil instrument is supplied with a voltage proportional to the current through an electrolytic cell 10, either by means of a shunt 2 or by a D.C. transformer. The other coil 3 has a voltage applied to it which is the difference between the voltage at the terminals of the cell 10 and a voltage equal to the E.M.F. of the cell which is tapped off from a potentiometer 5 supplied by a battery 4. The instrument may close relay contacts 8, 9 and thereby indicate whether the resistance is above or below the normal value. In a modification, Fig. 2, in which a number of electrolytic cells are connected in series, a voltmeter 11 is connected across each cell 10. A second circuit including a potentiometer 13 corresponding to each cell is' supplied by a D.C. current transformer 14. A voltmeter 12 is connected across the tapped-off portion of each potentiometer 13 and is graduated so that its zero reading corresponds to the E.M.F. of the corresponding cell. Each potentiometer 13 is adjusted so that when the current is at its normal value the voltmeter 12 indicates the desired voltage across the corresponding cell. The electrodes of the cells are then adjusted until the corresponding voltmeters 11, 12 are in agreement. In another modification, Fig. 4, a differential moving coil instrument is connected to each cell 10. One coil 15 of each instrument is connected across the corresponding cell, the other coil 20 being supplied from a potentiometer 17. These potentiometers are in a circuit supplied by a shunt multiplier 16 in series with a potentiometer 18 fed from a constant voltage source 19, so that the current through the potentiometers 17 is proportional to the current through the cells 10 increased by a constant current from the potentiometer 18. Contacts 21 or 22 are operated according as the resistance of the cell is above or below normal and may operate a signal or control automatic regulation.