It is a sensor to measure temperature of system continuously during its working whether cold or hot. It is known as permanent thermocouples also, because it is giving temperature continuously all ups & down.

It is a assembly in a long pipe of stainless or mild steel as shield. In side of shield two different metal element junction filled by suitable insulating material and on the top of pipe a head is there with ceramic terminal through that power supply providing. The thermocouple keeping in the system in a protective tube. The thermocouple work on seebeak theory.

This type of thermocouple widely use in industries like Rolling Mills, Killen, Textile, Power, Chemical, Cement etc & industrial and home appliances like safety devices cold storage, heater boiler, oven etc.

It is available on many types like J, K, T, E, R, S, B etc. Selection of type depend on requirement of system of which temperature to be measure. In one type sub types also, depend on selection of quality of shield, Insulating material, type of head etc . This type of thermocouple can be use -270 to 2200 centigrade on choosing type of thermocouples .