In industrial production, temperature is one of the important parameters that need to be measured and controlled. In the temperature measurement, the thermocouple is widely used, and it has many advantages such as simple structure, convenient manufacture, wide measuring range, high precision, small inertia and easy transmission of output signals. In addition, since the thermocouple is a passive sensor, it does not need an external power supply for measurement. It is very convenient to use, so it is often used to measure the temperature of the gas or liquid in the furnace, the pipe, and the surface temperature of the solid.

Thermocouple (thermocouple) is a commonly used temperature measuring component in temperature measuring instruments. It directly measures the temperature and converts the
temperature signal into a thermoelectromotive force signal, which is converted into the temperature of the measured medium by an electric meter (secondary meter). The shape of various thermocouples is often very different due to the needs, but their basic structure is almost the same, usually composed of hot electrode, insulating sleeve protection tube and junction box, etc., usually with display instrument, recording instrument and electronic adjustment Used in conjunction with the device.