GB1423136A - Heating element - Google Patents

Abstract

1423136 Resistance heating element POWER DEVELOPMENT Ltd 8 Jan 1973 [17 Feb 1972] 7387/72 Heading H5H An elongate heating element comprises one or more electrical conductors 12 extending longitudinally of and spaced from a surrounding open-ended solid walled metal sheath 10, the sheath being completely filled with resistive material 14 containing SiC or carbonaceous material such that when current is passed between the conductors 12 or between a conductor 12 and the sheath 10, heat is generated in the resistive material 14. The resistive material may be powdered carbon or silicon carbide or a ceramic, resin or phosphate bonded carbon or silicon carbide material. Ceramic bonded silicon carbide is made by mixing clay, graphite and silicon carbide and then pressing them. A ceramic bonded carbon resistor is made by adding carbon to a blend of high quality alumina and clays and then firing. The sheath may be of copper, stainless steel or rimming steel. The conductor(s) 12 may be solid wire, stranded wire, or cylindrical tube. The sheath may have an insulating external layer or standoff insulators. The element may be single or three phase. The element may be made by ramming the resistive material into a sheath containing the necessary conductors and then rolling or drawing the assembly down to the required diameter. Alternatively the resistive material may be extruded on to the central conductor or conductors prior to the addition of the metal sheath. The silicon carbide material provides self protection against voltage surges. The element may be bent to form a towel rail, may be used as an underfloor heater, as a wall heater, as a portable heater, in a storage-heater, or a runway or roadway heater.