GB939001A - Improvements relating to electric supply systems - Google Patents

Abstract

939,001. Supply systems for heating resistors. SATCHWELL CONTROLS Ltd. Dec. 21, 1961 [Jan. 3, 1961], No. 269/61. Class 38 (4). A system for supplying two loads comprises means whereby, after a given period from switching on, one of the loads is switched out of circuit. As described the two loads comprise two heating elements 12, 18 of an electric hotplate, initial movement of a control knob 5 causing contacts 6, 7 and 10, 11 to close whereby the element 12 is supplied in a series circuit with the heater 9 associated with the contacts 6, 7 whilst the element 18 in series with normally closed contacts 13, 15 form a circuit in parallel therewith. A heater 17 is associated with the contacts 13, 15 and when a predetermined period from switching on has elapsed the contacts 13, 15 open to remove the supply from the element 18 whilst the heater 9 causes the contacts 6, 7 to cycle, the ON-OFF ratio being determined by the control knob 5. Thus rapid initial heating of the hotplate is effected. Alternatively the contact 13 may be connected to contact 6 so that the cycling of contacts 6, 7 do not control the supply to the heater 18. In another embodiment a fourth switch, operated by the control knob 5, is provided in series with the element 18, the contacts closing only when the control knob 5 is moved to the full heat position.