Thermocouple and thermocouple temperature measurement on all belong to the contact temperature measurement, although the effect is same measuring the temperature of the object, but the principle and characteristics of them is different. Thermocouple temperature measurement is widely used in the temperature of the device, it is the main characteristic of wide measurement range, stable performance, at the same time, simple structure, good dynamic response, more can far eastone - 4 20 ma electrical signals to facilitate automatic control and centralized control. Thermocouple temperature measurement principle is based on thermoelectric effect. Connect the two different conductor or semiconductor into closed loops, when the two contacts in temperature is not at the same time, the circuit will produce thermoelectric potential, this kind of phenomenon called the thermoelectric effect, also known as the seebeck effect. Thermoelectric potential generated in closed loop is composed of two kinds of potential: the temperature difference between electric potential and contact potential. Although thermocouple is widely applied in industry, but because of its temperature range makes his application by certain restrictions, thermal resistance temperature measurement principle is based on the conductor or the resistance of the semiconductor characteristics of the changes with temperature changes. Its many advantages, can also remote transmission signal, high sensitivity, strong stability, compatibility and accuracy are better, but you need to power, can't instantaneous measured the change in temperature. There are two kinds of structure of the thermocouple, regular and type. Normal sexual thermocouples generally by the hot electrode, insulation tube, to protect casing and junction box parts, such as the type of thermocouple is the thermocouple wire, insulation material and metal protective casing combination after assembly, after stretching processing from a combination of a solid.