Voltage-Leveling Monolithic Self-Regulating Heater Cable

Abstract

A self-regulating electric heater cable includes a monolithic heater core of PTC material encapsulating a pair of bus wires, and a conductive layer disposed on an outer surface of the heater core such that the conductive layer levels the voltage generated at the outer surface of the heater core when an electric current is passed through the bus wires. The conductive layer draws the current evenly through lobes of PTC material encapsulating the bus wires. The conductive layer may be a coating, such as a conductive ink or paint, or may be an extruded or wrapped material applied to the heater core. Standard heater cable layers are applied over the conductive layer, including an electrically insulating layer that contacts a portion of the conductive layer and also may be separated, at points, from the conductive layer by one or more air gaps.

Dependencies are inferred from the claim text.