ELECTRICAL HEATING ELEMENTS

摘要

An electrical heating element for use, for example, in a domestic iron and comprising essentially a metallic base plate having a coating of a glass ceramic dielectric upon which is laid an electrically resistive track produced from a platinum-containing material whose electrical conductivity falls as its temperature rises thus providing a self-limiting characteristic for the element. The resistive track is covered with further dielectric material and the element is incorporated along with appropriate control circuitry and equipment, into an appliance to be heated. The resistive track has a temperature coefficient of resistance which is sufficiently positive that at a pre-determined maximum temperature its electrical resistivity is at a level at which the rate of electrical energy absorption is substantially equal to the rate of heat loss.