Termopaaria

Termopaaria, or thermocouples, are temperature sensors that use the Seebeck effect: two dissimilar metals joined at a sensing junction produce a small electrical voltage when there is a temperature difference between the sensing junction and a reference junction. The output voltage is proportional to the temperature difference, and the sensor requires cold junction compensation to relate the measurement to an absolute temperature.

Thermocouples are constructed from pairs of metal alloys, most commonly in bare wire form or enclosed in protective sheaths made of stainless steel, mineral insulation, ceramics, or other materials. The choice of metal alloy determines the temperature range, chemical compatibility, and sensitivity. Common types include K (Chromel–Alumel), J (Iron–Constantan), T (Copper–Constantan), E (Chromel–Constantan), N (Nicrosil–Nisil), and high-temperature types S, R, and B (Platinum–Rhodium alloys). Each type has a characteristic operating range, sensitivity, and real-world accuracy, and some are better suited for reducing or oxidizing atmospheres or high-temperature environments.

Key considerations for use include non-linearity of the voltage–temperature relationship, drift over time due to aging, and potential self-heating effects from the measurement current. Accuracy is specified by tolerance classes defined in standards such as IEC 60584. Proper installation also requires compatible cold-junction compensation and avoidance of mixing sensors of different types or incompatible connectors.

Applications span broad industrial, laboratory, and automotive contexts, including process control, furnaces, kilns, engines, and environmental monitoring. Thermocouples are valued for their wide temperature ranges, ruggedness, fast response, simple construction, and relatively low cost, though they require careful calibration and appropriate signal conditioning.