GB532171A - Improvements in and relating to temperature controlling devices, particularly suitable for controlling the temperature of electric heating apparatus such as boiling plates - Google Patents

Abstract

532,171. Mercury switches; control systems for heating resistances. BRITISH THOMSONHOUSTON CO., Ltd., and SIMS, W. J. Aug. 18, 1939, No. 23879. [Class 38 (v)] [Also in Group XXXV] A boiling plate or the like 5 can be continuously energized to bring a vessel thereon quickly to the boil, by rotating the container 1 anti-clockwise from the Fig. 2 position, so causing one or more of the parallel-connected electrodes 3 to dip into the mercury 2. The container is then further rotated to remove the electrodes 3 from the mercury, but the electrode 7 dipping into the mercury makes a circuit to a heating coil 8 which boils the mercury to a degree depending on the amount of resistance 10 in the circuit. The resulting ebullition causes momentary contacts to be made with the electrodes 3, and a number of impulses to be sent through the apparatus 5 for simmering purposes. The electrode-tips may all lie on a plane parallel to the mercury level in the "simmering " position. The coil 8 may be mounted in a recess in the container wall or its container may be incorporated in the side of the container 1 itself, and its turns may be in air or in good heat-conducting, electrically-insulating material, or it may comprise a wire wound in a nitrogen-containing vessel. Resistance 10 may be in the form of a mercury-container mounted so as to be rotatable with container 1, the resistance being tapconnected to contacts engaged in succession by the mercury. The container may itself be gasfilled.