Thermocouples |
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Thermocouples work on the
Seebeck principle, discovered accidentally in 1822 by an Estonian physician named Thomas Seebeck. Basically, the
Seebeck principle explains how two dissimilar metals generate a temperature-dependent flow of current at their
welded junction when attached to a closed circuit. Seebeck discovered that a compass needle would be deflected when a closed loop was formed of two metals joined in two places with a temperature difference between the junctions. The metals respond to temperature by assuming different voltage potentials, thereby generating a current related to the temperature of the junction. This table lists the properties of the most common thermocouple junctions.
Thermocouple types R, S, and B are constructed of platinum and rhodium, and are referred to as noble metal thermocouples. They are more accurate and more stable than base metal types, but are more expensive.
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