Importance

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Abstract

Disclosed is a heating resistor comprising a body of a ceramic PTC resistor material with at least one face of the body coated by a layer of an NTC material. The combination of a PTC resistor and an NTC resistor limits the inrush current at the beginning of a heating process when the PTC resistor is still cold and therefore has a low electrical resistance. When the resistor is heated, the electrical resistance of the NTC resistor decreases while the electrical resistance of the PTC resistor increases. Thus, the electric current changes less until the PTC resistor reaches its critical temperature where its electrical resistance increases by several orders of magnitude. The lowering of electrical current at the beginning of the heating process is especially advantageous in applications that rely on a limited power supply, for example a car battery.

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First Claim