Thermocouple is one of the industry commonly used temperature detecting element, the working principle of the thermocouple is based on baker ( seeback) Effect, that is, two different components of conductor ends connected into a circuit, such as two different connection end temperature, then to produce the physical phenomenon of thermal current in the circuit. The advantage is; 1) high precision measurement. Because of thermocouple direct contact with the object being measured, not affected by intermediate medium. (2) the measurement range. The commonly used thermocouple from - 50 ~ + 1600 ℃ can renew edge measurement, some special thermocouple with low temperature to - 269℃（ Such as gold iron nickel chrome) High, up to + 2800 ℃ ( Such as tungsten - Rhenium) 。 3. Simple structure, easy to use. Thermocouple is usually composed of two different kinds of metal wire, but is not limited by the size and the beginning of, outside has protective casing, which are very convenient. Basic principle of thermocouple temperature measurement will be two different welding material A conductor or semi-conductor A and B to form A closed loop, when the conductor A and B two persistent point temperature difference between 1 and 2, occurs between the electromotive force, and thus form the size of A current in the circuit, this kind of phenomenon called the thermoelectric effect. Thermocouple is in using this effect to work. Commonly used in low temperature zone thermocouple is a kind of temperature detector. Its main characteristic is high accuracy, stable performance. The platinum thermocouple measuring accuracy is high, it is not only widely used in industrial temperature measurement, and is made into standard benchmark instrument. Pt100: used for thermocouple, thermocouple, temperature meter, temperature transmitter, pressure differential pressure transmitter, hot runner heater, compensation cable, control cable, etc. Cu50: used for thermocouple, thermocouple thermometer, thermocouple checking instrument, thermocouple simulator - Thermocouple simulators, copper thermocouple, thermocouple, etc. Pt100 and cu50 measuring temperature is different, pt100 measurement of high temperature, cu50 measuring the temperature of the low.