Termopaarin

Termopaarin is the Finnish term for a thermocouple, a temperature sensor that relies on the thermoelectric Seebeck effect to generate a voltage from the temperature difference between two dissimilar metals joined at one end. A termopaarin typically consists of two conductors of different alloys connected at a measuring junction, with a second junction (the reference or cold junction) kept at a known temperature or compensated in software or circuitry. The output voltage is proportional to the temperature difference and is usually in the tens of microvolts per degree Celsius, requiring proper calibration and cold-junction compensation to yield accurate temperature readings.

Common thermocouple types include K-type (Chromel–Alumel), J-type (Iron–Constantan), T-type (Copper–Constantan), and E-, N-, S-, R-, B-type pairs. Each type offers different temperature ranges and sensitivities, with K-type being the most widely used due to its wide range (-200 to about 1350 C) and robustness. However, accuracy is affected by junction condition, aging, and exposure to corrosive environments; nonlinearities and drift may occur, especially at high temperatures or in oxidizing atmospheres.

Applications span industrial process control, combustion monitoring, kilns, gas turbines, automotive sensors, and laboratory experiments. Installation considerations include proper protection (sheaths, insulation, and shielding), calibration against known references, and accounting for thermal gradients along the wire. The Seebeck effect was discovered in 1821 by Thomas Seebeck, and thermocouples have been standardized and widely adopted since the mid-20th century.