GB761258A - Improvements in and relating to liquid resistance controllers - Google Patents

Abstract

761,258. Liquid resistors. ENGLISH ELECTRIC CO., Ltd. Dec. 31, 1954 [Jan. 1, 1954], No. 57/54. Class 37. A variable liquid resistor comprises a movable and a fixed electrode structure housed within an electrolytic tank, the movable structure being arranged beneath the fixed structure and being arranged for movement vertically towards or away therefrom. Fig. 1 shows an arrangement comprising three such variable resistors, arranged in star connection, for use in controlling the speed of induction motors ; -the Figure shows only one set of fixed and movable electrodes. The fixed electrodes 17 are supported by leads 12 arranged with an insulating tube 14 and the movable electrode 19 is supported by a lead 20 arranged within an insulat. ing tube 21. The movable electrodes 19 are carried by an overhead cross bar 25 which is supported at its ends by piston rods 26. The piston rods 26 may be moved vertically up or down by means of fluid pressure applied to the pistons 27 within the cylinders 28, thus providing for variation of the resistance between the electrode 17 and 19. Each set of fixed and movable electrodes is arranged within a cylindrical " chimney " 32 provided with vents at their tops and bottoms to allow the liquid to circulate through them. The baffles 35 are arranged between the chimneys to increase the parallel resistance between pairs of fixed electrode structures 17. Fig. 2, which is a sectional side elevation on the line B-B of Fig. 1, shows the form of the fixed and movable electrodes. It is stated that when the movable electrode 19 is moved from its lowermost position to an intermediate position 36 the resistance falls at a uniform rate. When it is moved from the intermediate position 36 to its uppermost position 37, the resistance decreases at a slower but still uniform rate. In a modification, Fig. 3 (not shown) the chimneys are tapered towards their lower ends and as before the rate of decrease of resistance is initially large and then falls to a smaller value as the movable, electrode is moved upwards from its lowermost position. In a second embodiment shown in plan view in Fig. 5 the three pairs of electrode structures are arranged within an anuular tank 110 the movable electrode 119 being attached to a triangular plate which is moved vertically by means of a pressure-operated piston disposed within the cylinder 128. Electrodes are disposed within part annular chimneys 132.