The Working Principle Of Thermocouple

When two kinds of material with different components compose a conductor loop, there is a temperature gradient, and will be current through the loop. At this time, there will be the electromotive force between the two ends and this is called the Seebeck effect (Seebeck effect), which is the working principle of thermocouple. These two different homogeneous conductors work as the thermodes, and the end with higher temperature is a working end, while the other one with the lower temperature is a free end, the free end usually at a constant temperature. According to the function relationship between temperature and the electromotive force, we can make the thermocouple indexing table; indexing table is obtained under the conditions that the temperature of free end is at zero degree Celsius below, different thermocouples with different indexing table.

When the thermocouple loop is connected with the third metal material, as long as the two contact of the material are in the same temperature, the electromotive force generated by the thermocouple will remain unchanged, which is not affected by the third kinds of metallic access in the loop. Therefore, while the thermocouple is measuring the temperature, we can access measurement instruments, and once the electromotive force is measured, we can know the temperature of the measured medium.