An ice bath is used to create a known reference temperature (0 °C).
Once the reference temperature and thermocouple type are known,
the temperature of the measurement thermocouple can be calculated.
The T-type thermocouple is a unique case since one of the conductors
(copper) is the same metal as the internal
DMM’s input terminals.
If another type of thermocouple is used, two additional thermocouples
are created. For example, take a look at the connections with a J-type
thermocouple (iron and constantan):
Two additional thermocouples have been created where the iron (Fe)
lead connects to the internal
DMM’s copper (Cu) input terminals.
Since these two junctions will generate opposing voltages, their effect
will be to cancel each other. However, if the input terminals are not at
the same temperature, an error will be created in the measurement.
Ice Bath
Internal DMM
Ice Bath
Internal DMM
Chapter 8 Tutorial
Measurement Fundamentals
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