Explain in detail the temperature measurement conditions of the thermocouple

Thermocouple is a kind of temperature sensing element, it is a kind of instrument, thermocouple directly measures temperature. A closed loop composed of two conductors with different composition materials. Due to the different materials, different electron densities produce electron diffusion, and a potential is generated after a stable equilibrium. When there is a gradient temperature at both ends, a current will be generated in the loop, and a thermoelectromotive force will be generated. The greater the temperature difference, the greater the current. After measuring the thermoelectromotive force, the temperature value can be known. In practice, a thermocouple is an energy converter that converts thermal energy into electrical energy.

The technical advantages of thermocouples: thermocouples have a wide temperature measurement range and relatively stable performance; high measurement accuracy, the thermocouple is in direct contact with the measured object, and is not affected by the intermediate medium; the thermal response time is fast, and the thermocouple is sensitive to temperature changes; The measuring range is large, the thermocouple can measure the temperature continuously from -40~+1600℃; the thermocouple has reliable performance and good mechanical strength. Long service life and easy installation. The galvanic couple must be composed of two conductor (or semiconductor) materials with different properties but meeting certain requirements to form a loop. There must be a temperature difference between the measuring terminal and the reference terminal of the thermocouple.

The conductors or semiconductors A and B of two different materials are welded together to form a closed loop. When there is a temperature difference between the two attachment points 1 and 2 of the conductors A and B, an electromotive force is generated between the two, thus forming a large current in the loop. This phenomenon is called the thermoelectric effect. Thermocouples work using this effect.