Introduction to Engineering Experimentation If a thermocoupl

Introduction to Engineering Experimentation

If a thermocouple circuit does not include a standard reference junction...(more than one answer may be correct)

A. a single “dummy” reference junction must be added

B. a pair of “dummy” reference junctions must be added

C. the table composed for standard reference still can be used

D. the circuit must be calibrated “from scratch”

Solution

Answer: C &A

Requirement of thermocouple is that it must have two junctions. Measurement (i.e. hot) junction and reference (i.e. cold) junction . Now if the standard reference cold junction is replaced by another junction, still we can measure the temperature by referring standard table.

Example: Let\'s say the reference junction is ice bath having temp. 0deg.C.

This can be replace by another junction with ambient temperature( let\'s say 20deg.C) and for this standard reference table can be used to add the difference in reference junction temperature to the measured value.

If the circuit does not have a reference junction at all, then option A is required along with option C.