Thermocouples

Thermocouples are the most commonly used temperature sensors.

A thermocouple is created when two dissimilar metals touch and the contact point produces a small open-circuit voltage that corresponds to temperature. This thermoelectric voltage is known as Seebeck voltage and is nonlinear with respect to temperature. Thermocouples require signal conditioning.

Thermocouple types differ in composition and accurate range:

Thermocouple TypePositive ConductorNegative ConductorTemperature Range (°C)
JIronConstantan–210 to 1200
KChromelAlumel–270 to 1372
NNicrosilNisil–270 to 1300
RPlatinum-13% RhodiumPlatinum–50 to 1768
SPlatinum-10% RhodiumPlatinum–50 to 1768
TCopperConstantan–270 to 400
BPlatinumRhodium0 to 1820
EChromelConstantan–270 to 1000