T-type thermocouple materials and characteristics

T-type thermocouple, that is, copper-copper-nickel thermocouple, also known as copper-constantan thermocouple, has a theoretical temperature measurement range of –270~+400 degree and an electromotive force range of -6.258-20.872mV. T-type thermocouple is an optimal thermocouple for measuring low-temperature cheap metals, mainly used in the military industry. Its positive electrode (TP) is 99.95% pure copper, and its negative electrode (TN) is a copper-nickel alloy, often called constantan (55% copper-45% nickel).

T-type thermocouple has the advantages of good linearity, large thermoelectric electromotive force, high sensitivity, high accuracy, good homogeneity of thermocouple wire, and low price. It is suitable for reducing atmosphere, especially at low temperatures of -200~0 degree . It has good characteristics and better stability. The annual stability can be less than ±3μV. After low-temperature verification, it can be used as a second-class standard for low-temperature value transfer. Because copper has poor oxidation resistance at high temperatures and is easy to fall off, it is generally used within 300 degree . When the temperature is below -200 degree , the thermoelectric potential decreases rapidly with the temperature, and the thermal conductivity of copper is high, which easily introduces errors at low temperatures. The tolerance level is divided into IIIIII, where level I is the high precision level.