Intab PC-Logger 3100i How To Use Manual page 15

5.4.2 Cold Junction Compensation
When using thermocouples to measure temperature it is almost always
necessary to know the temperature of the "cold junction". Thermoelectric
voltage has to be "adjusted" with respect to this temperature.
Thermoelectric voltage is the result of the temperature difference between
the cold junction and the hot junction.
A solid state temperature sensor has been placed centrally in the screw
terminal area of the analogue board. Its temperature is automatically sampled
every time a temperature measurement is taken. All temperature
measurements are thus compensated for the actual temperature of the
terminals themselves.
Some precautions have to be taken if the "3100i" is exposed to rapid
temperature gradients. Since temperature is measured in one point only, a
gradient from one side of the unit to the other may cause misreadings.
By giving the unit time to reach a stable temperature before recordings are
started and by protecting it from sudden changes of ambient temperature a
very high degree of accuracy can be achieved.
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BASIC UNIT