STP470B: Chapter 7—Reference Junctions

    Pages: 9    Published: Jan 1981


    Abstract

    A thermocouple circuit is by its nature a differential measuring device, producing an emf which is a function of the temperatures of its two junctions. One of these junctions is at the temperature which is to be measured and is referred to as the measuring junction. The other junction is maintained at a known temperature and is referred to as the reference junction. (In a practical thermocouple circuit (see Section 2.3) copper wires are often connected to the thermocouple alloy conductors at the reference junction. The term reference junctions will be used to refer to this situation.) If these junctions are both at the same temperature, the presence of the copper “intermediate metal” introduces no change in the thermocouple's emf. If they are not at the same temperature the analysis of the circuit is complicated. Moffat [1] gives a helpful analytical method.


    Paper ID: STP27358S

    Committee/Subcommittee: E20.04

    DOI: 10.1520/STP27358S


    CrossRef ASTM International is a member of CrossRef.