Accession Number : AD0630750

Title :   THERMOCOUPLE CORRECTIONS FROM IRREVERSIBILITY THEORY.

Descriptive Note : Technical summary rept.,

Corporate Author : MATHEMATICS RESEARCH CENTER UNIV OF WISCONSIN MADISON

Personal Author(s) : Gaggioli,R. A. ; Mitchell,J. W.

Report Date : JAN 1966

Pagination or Media Count : 14

Abstract : The resultant error introduced by using finite impedance measuring instruments in thermocouple circuits was determined quantitatively and rigorously. The standard-practice correction formula to account for finite impedance of measuring instruments in thermocouple circuits is valid (provided there are no excessive radial temperature and voltage gradients). The measured voltage can be corrected to give voltage values for use with standard tables. The analysis shows that error is reduced by decreased thermocouple circuit resistance R(TC) (including all lead wires) and increased instrument impedance (internal impedance of instrument alone). The effect of the temperature dependence of the electrical conductivity and the absolute thermoelectric power are exactly accounted for by an equation which requires that the total resistance R(TC), which is dependent upon the temperature variation along the wires, be determined. A procedure was also indicated that minimizes the effect of unequal lead-wire junction temperatures.

Descriptors :   (*THERMOCOUPLES, CORRECTIONS), (*THERMODYNAMICS, IRREVERSIBLE PROCESSES), THERMOELECTRICITY, ELECTRICAL IMPEDANCE, ERRORS, VOLTAGE, ELECTRICAL RESISTANCE, TEMPERATURE, ELECTRICAL CONDUCTIVITY, ELECTRIC WIRE

Subject Categories : Test Facilities, Equipment and Methods
      Thermodynamics

Distribution Statement : APPROVED FOR PUBLIC RELEASE