Switch controlled, zone-type heating cable and method

摘要

A parallel, zone-type heating cable wherein thermally-controlled ferrite reed switches in each zone regulate current flow to heating elements aligned in parallel with each other. Two parallel conductors deliver current to the switches and the heating elements. A dielectric insulation material separates the conductors from each other and the heating elements. The heating cable may further include a component having a particular temperature coefficient of resistance aligned in parallel with the switch to further regulate current flow to a positive but lesser level when the switch is open.