Commonly used in low temperature zone thermocouple is a kind of temperature detector. Its main characteristic is high accuracy, stable performance. The platinum thermocouple measurement accuracy is high, yes it is not only widely used in industrial temperature measurement, and is made into standard benchmark instrument. Thermocouple temperature measuring thermocouple temperature measurement principle and the material is based on the metal conductor resistance value increases with the increase of the temperature of the properties for temperature measurement. Thermocouples are mostly made of pure metal materials, the application is a lot of platinum and copper, in addition, now has started using survey, nickel, manganese and rhodium thermocouple materials such as manufacturing. The structure of thermocouple thermocouple industry commonly used thermocouple temperature sensing element ( The resistor body) The structure and characteristics. From the thermocouple temperature measurement principle, the measured the change in temperature is directly measured by thermocouple resistance change, therefore, the wires of a thermocouple body such as a variety of wire resistance change will affect temperature measurement. As to eliminate the influence of the lead resistance with the three wire or four wire system.