A thermocouple is a device used to measure temperature in industrial manufacturing processes. When the temperature is raised to a certain value, it is necessary to maintain and control it consistently. For temperature measurement, the thermocouple is connected to a measuring instrument, such as a Temperature Controller, Recorder, Digital Temperature Indicator, etc.
A thermocouple operates on the principle of converting heat or temperature changes into electrical voltage. This is done by joining two dissimilar metal wires with different chemical properties at one end, which is called the 'hot junction' (T1) and is the point used for temperature measurement. The other ends of the two metal conductors are left open, and this point is called the 'cold junction' (T2). If the hot junction and cold junction have different temperatures, the two metal conductors will expand, and a current will flow through them, resulting in a potential difference at the open ends of the metal conductors.
Currently, there are many types of thermocouples for different applications. Each type consists of two different metals and has a different temperature measurement range. However, in industries where thermocouples are used for temperature measurement, Type K thermocouples are most commonly used because they are relatively inexpensive and have a wide temperature measurement range that covers various applications.