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 type T thermocouple is a unique case since one of the conductors (copper)
is the same metal as the meter’s input terminal. If another type of
thermocouple is used, two additional thermocouples are created. For
example, the connections with a type J thermocouple (iron and constantan):
Two additional thermocouples have been created where the iron lead
connects to the meter’s copper 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, then an
error will be created in the measurement.
Meter
Ice Bath
Meter
Ice Bath
Chapter 7 Measurement Tutorial
Measurement Techniques and Sources of Error
266
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