GB532391A - Improvements in or relating to electric heating apparatus suitable for cooking and other purposes - Google Patents

Abstract

532,391. Electric resistance heaters; current supply. BERRY, A. F. July 21, 1939, No. 21237 [Class 39 (iii)] [Also in Group XXXV] In order to reduce the maximum voltage on the heating elements of cooking apparatus, instead of connecting an intermediate point of the element to earth as in Specification 388,429, the element is supplied through the low-tension secondary 2 of a transformer, an intermediate point of which is connected to earth. As shown applied to an all-purposes cooking equipment, the hot plate 7 is connected as described above and a graded grill with mid-point earthed is similarly connected. Two hot plates 4 with elements earthed at one end are supplied from the two halves of a centrally earthed auto-transformer 5 connected across the centrally-earthed secondary 2 and provided with tappings to switches 6 whereby the supply to the plates 4 may be separately controlled. The heating elements may consist of coiled heating resistances packed in tubular containers the diameter of the coil at the terminal supply end being smaller than at the central earthed end, so that the heating effect and the necessary insulation is reduced at the supply end. An equivalent result may be obtained by using a resistance element of uniform diameter within a tapering tube.