Cu-CuNi thermocouple (type T) is also named Cu- Constantan thermocouple. The positive leg Cu(TP) is made by pure Copper, and the main chemical composition of negative leg Constantan (TN) is Cu: Ni≈ 55%: 45%. Although EN, TN, JN are all called Constantan, TN and EN don not give the same EMF output curve as JN. EN and TN are able to interchange but they are not interchangeable with JN. The operating temperature range of type T thermocouple is -200~350℃, Due to the low resistance of oxidation that Copper has, it is not advisable to go beyond that range.