Thermocouple

A thermocouple is a temperature sensor consisting of two wires made of different metals joined at one end (the junction). When the junction is heated or cooled, it produces a small voltage (the Seebeck effect) that is proportional to the temperature. Common types include Type K (-200°C to +1,260°C) and Type T (-200°C to +350°C).

Thermocouples are rugged, inexpensive, and can measure extremely wide temperature ranges. However, they are less accurate than PT100 RTD sensors and can drift over time, requiring more frequent calibration.

Thermocouples are used where extreme temperatures or rugged environments make other sensor types impractical — such as autoclaves, ovens, cryogenic storage, and industrial furnaces. Their fast response time also makes them suitable for processes where temperature changes rapidly.