GB1324861A - Liquid resistor apparatus - Google Patents

Abstract

1324861 Variable liquid resistors N R BEYRARD 27 Aug 1970 [27 Aug 1969] 41401/70 Heading HIS Pressure developed in a vapour generator is used to alter the effective cross-section of the current path between two electrodes by either varying their depth of immersion in a liquid (Fig. 2) or inserting an insulating plate between them (Fig. 3). In the first embodiment (Fig. 2) a pulsed electric current operating a valve 8 releases liquid which falls on a heated dish 7 and vaporizes, the resulting increase in pressure in the vapour generator 6 inflating the bellows 5 which raises rods 2a, 3a, to reduce the depth of immersion of the electrodes 2, 3. Alternatively the bellows 5 may be replaced by a piston-andcylinder arrangement. A safety valve 9 prevents excess pressure from developing in the vapour generator, and cooling fins (11, Fig. 1, not shown) encourage condensation, the liquid then escaping through capillary drainage means 10. In another embodiment (Fig. 3) the vapour is generated by a current passing between electrodes 16, 17, partially immersed in liquid. The bellows 5A, 5B raise and lower an insulating partition 15 to alter the effective surface area of the electrodes (2, 3, Fig. 4) which are held about 1 cm. apart. By suitably shaping the electrodes (2c, 3c) the change in resistance caused by moving the partition may follow a chosen non-linear law. Distilled water is used as the liquid in both embodiments, and as another alternative the level of the water may be varied while keeping the electrodes stationary. When fully extended the bellows can be made to actuate a switch to short-circuit the electrodes after, for example, having been used in starting up an asynchronous motor.