Basics of Electrical Engineering and Thermodynamics

Copper is one of the best conductors industrially used. Nevertheless copper is the raw material for electrical resistance heatings. This relationship will be explained by using the following basic physical laws. They also form the basis for understanding the contacting of the electrical panel heating, its performance, as well as the heat transfer from the conductors to the heated medium.

 

Starting point is Ohm's law

If current flows trough a resistance R, a voltage U is measurable. The electrically absorbed power in the consumer is determined by

In an electrical resistance heating, this power is converted into heat. In case of CoTexx® Knitted Heating Fabric the resistance consists of thin metal wires. The internal friction of the electrons in the lattice represents a resistance to the current flow, resulting in the heating of the conductor. Because of the resistance of an electrical conductor according to the relationship

the cross-sectional area A of the installed wires must be small and their length l long.

 

The layout of the heating needs to take into account the temperature dependence of the electric resistance.

In this equation α describes the linear temperature coefficient of the resistance, a material-dependent constant. In the case of copper α=0,0039 [1/°C]. For example, if the resistance of one web of knitted heated fabric at 20 °C is 1 Ω, at 150°C 1,51 Ω is measurable.

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