GB819548A - Improvements in and relating to liquid resistance controllers - Google Patents

Abstract

819,548. Liquid resistances. ENGLISH ELECTRIC CO. Ltd. Jan. 30, 1958 [Feb. 5, 1957], No. 3963/57. Class 37. A liquid resistance controller comprises at least one assembly of conducting plates mounted in an electrolytic tank, and for each assembly a movable barrier means. The plates are disposed adjacently in parallel planes, alternate plates being electrically connected together to form two interleaving electrodes. The associated barrier means comprises a number of insulating plates arranged for movement in the spaces between adjacent electrode plates to vary the cross-sectional area of the current paths between electrodes. In the embodiment shown, a resistance controller comprises a tank 10, half filled with electrolyte, which has mounted therein a supporting cradle 11 carrying conducting electrode plates 16 which constitute the assembled pair of electrodes, and which are connected to terminals 19a and 19b. The plates 16 are all of similar segmental form, but some have openings 20 formed so that they have different conducting areas. Flat insulating side plates 21 of semicircular shape cooperate with an insulating lining 12 of the cradle 11 to enclose the assembled electrodes in an insulating cell and thus reduce leakage from the electrodes to the tank 10 by the electrolyte. A rotatable shaft 22 mounted above the plates 16 has mounted thereon a number of flat parallel barrier vanes 24 made of insulating material. Rotation of the shaft 22 causes the barrier vanes 24 to be moved into and out of the inter-electrode plate space, thus varying the resistance between electrodes by varying the cross-sectional area of the current path. The electrolyte is supplied through the inlet manifold 29, passes round the plate 16 and spills over two weirs 32, 33 into the lower part of the tank 10 and out through the pipe 34. The weirs are so disposed that the greater part of the electrolyte flows towards the weir 33, thus passing across the low resistance end of the electrodes, that is through the spaces where the greatest amount of heat is dissipated when the barrier vanes are in the minimum resistance condition. Movement of the barrier vanes up to the point where the plates D become completely shielded varies the resistance value between adjacent conducting plates by varying the effective cross-sectional area of the conducting paths between these plates, effective conducting path lengths being substantially unaltered by movement of the barrier vanes. With subsequent movement of the barrier vanes first the plates D then the plates C and finally the plates B become completely shielded with the result that the number of parallel paths is reduced whilst at the same time the lengths of at least some of them is increased. After the point is reached at which plates B become completely shielded, the conducting path is between the plates A only and is 15 interelectrodes spaces long. The rate of change of resistance is thus made to increase with increasing resistance and the resistance between the two electrodes can be made to vary in a logarithmic manner. A three phase controller may be similarly constructed by assembling three units as described above into a common tank, the units being electrically separated by the enclosing insulating side plates.