T-type thermocouple is also known as copper-constantan thermocouple (copper/nickel-copper thermocouple, graduation number T, measuring range -200~+350℃), and it is also the best thermocouple for measuring low temperature and cheap metals. Its positive electrode (TP) is pure copper, and the negative electrode (TN) is a copper-nickel alloy, which is often constantan. It is commonly used with Ni-Cr-Constantan constantan EN, but not with iron-Constantan constantan JN. Although they are called constantan, the measuring temperature range of copper-copper-nickel thermocouples is -200~350℃.
T-type thermocouple has the advantages of good linearity, large thermoelectromotive force, high sensitivity, approximate linear temperature and good reproducibility, fast heat transfer, good stability and uniformity, and low price, especially at -200~0℃ Used in the temperature zone, the stability is better, the annual stability can be less than ±3μV, and can be used as a second-class standard for low temperature value transfer after low temperature verification. The positive electrode copper of the T-type thermocouple has poor oxidation resistance at high temperatures, so the upper limit of the operating temperature is limited.
Since the thermoelectric characteristics of various types of thermocouples are different, it is best to use them within the range of their linear segments. At the same time, each type of thermocouple has the highest temperature limit used.
The highest temperature corresponding to different specifications of T-type thermocouples (the thin thermocouple is easy to break, and the smaller the diameter of the thermocouple, the lower the temperature used):