A thermocouple is a sensor for measuring temperature. This sensor consists of two dissimilar metal wires, joined at one end, and connected to a thermocouple thermometer or other thermocouple-capable device at the other end. When properly configured, thermocouples can provide temperature measurements over wide range of temperatures.

Thermocouples are known for their versatility as temperature sensors therefore commonly used on a wide range of applications – from an industrial usage thermocouple to a regular thermocouple found on utilities and regular appliances. Due to their wide range of models and technical specifications, it is extremely important to understand its basic structure, how it works, its ranges as to better determine what is the right type and material of thermocouple for your application.

How does a thermocouple work?

When two wires composed of dissimilar metals are joined at both ends and one of the ends is heated, there is a continuous current which flows in the thermoelectric circuit. If this circuit is broken at the center, the net open circuit voltage (the Seebeck voltage) is a function of the junction temperature and the composition of the two metals. Which means that when the junction of the two metals is heated or cooled a voltage is produced that can be correlated back to the temperature.

Thermocouple types

Thermocouples are available in different combinations of metals or calibrations. The most common are the “Base Metal” thermocouples known as Types J, K, T, E and N. There are also high temperature calibrations – als known as Noble Metal thermocouples – Types R, S, C and GB.