Working principle and structure of thermocouple Maintenance post 1.Understand how it works 1.1Thermocouple temperature measurement principle: two conductors with different electronic density form a closed circuit. If the temperature of the two joints is different, there will be current in the circuit. This phenomenon is called thermoelectric phenomenon. The corresponding electromotive force is called thermoelectric potential or thermoelectric potential. It has a certain functional relationship with the temperature. Using this relationship, the temperature can be measured.This phenomenon includes the following principles: Peltier's theorem: different materials are combined together to generate electric potential at the joint surface.Thomson's theorem --- electric potential caused by temperature difference.When the conductor material of the thermocouple is uniform, the size of its thermal potential has nothing to do with the length and diameter of the conductor itself, only with the composition of the conductor material and the temperature of both ends.Therefore, thermocouples of various uses can be made with different conductors or semiconductors to meet the needs of measurement of different temperature objects. 1.2Three laws of thermocouples Law of homogeneous conductor
A closed circuit made of a single homogeneous metal will not generate current even if the temperature changes at every point along the circuit.That is, e = 0.
In the thermocouple circuit formed by two homogeneous metal materials a and B, the correlation function between the thermoelectric potential E and the temperature T1, T2 at the junction is not affected by the