GB804453A - A switch circuit for electric heating appliances, more particularly hotplates or boiling plates - Google Patents

Abstract

804,453. Switching arrangements for heating resistors. JACKSON INDUSTRIES, Ltd. (Fischer, K.). Sept. 28, 1956, No. 29724/56. Class 38 (4). [Also in Group XI] An electric heating appliance comprising a plurality of heating elements has one element in the form of a supplementary element which can be switched on manually to accelerate the initial heating and cut out automatically by a heat-operated switch after a predetermined time, the supplementary element also being available for manual series and/or parallel switching operations. An electric cooker has three heating elements X, Y, Z, the element Z forming a supplementary element associated with which is a bimetallic switch S, the heater coil d of which can either be connected in series or in parallel with the element Z. Operation of a manual switch S1 to the " high heat " position connects line P1 to connections e, f and line P2 to connections g, h. In this position elements X, Y are in parallel giving the highest heating condition for the hot-plate 1, the supplementary element Z also being in parallel over the bimetallic switch S to give rapid initial heating of the hot-plate. After a predetermined timesay seven minutes-the switch S operates to open its contacts a, b to remove the element Z from circuit, the hot-plate then continuing to operate in the " high heat " manner with the elements X, Y in parallel on the supply. The contacts a, b remain open due to their position below the hot-plate, where they are influenced by the heat from the hot-plate. In Fig. 6 the switch S and the manual switch S1 are each shown attached to one of the legs 3 supporting the hot-plate 1. Operation of the manual switch S1 to other heat positions gives various single, series and/or parallel connections of the elements, the supplementary element Z being used in the " low heat " position where all three elements X, Y, Z are in series across the supply. With such a connection the heat developed in the switch heater coil d is insufficient to open contacts a, b, thus allowing the element Z to remain in circuit. After rapid initial heating, should the manual switch S1 be operated to other heat positions the bimetal switch returns to a condition where it will again afford rapid heating if desired.