Tutorial 7
Keysight 34970A/34972A User’s Guide 281
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.
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