User Manual

I-7011, I-7018 User Manual Rev:B1.0

To measure the Seebeck voltage directly is not available

because we must first connect a voltmeter to the thermocouple,

and the voltmeter leads themselves create a new thermoelectric

circuit. Therefore we need to eliminate the junction thermoelec-

tric to measure the correct Seebeck voltage, and this is called “Cold

Junction Compensation”.

For most thermocouples, the Seebeck voltage is 0V while

in 0°C. One simple way to cancel the junction voltage is to put the

junction into 0°C enviroment and the junction voltage is 0V.

Normally, this is not a good method for most application. Typical

method is to measure the junction temperature by thermistor, and

measure the junction voltage from the junction temperature. Then

we may get the Seebeck voltage from measured thermocouple

voltage and junction voltage, and we may calculate the tempera-

ture from the Seebeck voltage.