New method for calculation the error of temperature difference measurement with platinum resistance thermometers (PRT)

Abstract

PRTs are often used for precise measurements of temperature difference in laboratories and industrial installations. For the range between 0 °C to 661 °C Standard EN 60751 defines the equation for PRT resistance vs temperature relation as quadratic equation. Therefore calculations characteristics of the temperature difference measured as two resistances of the two thermometers implies calculation the roots of many quadratic equations. This paper presents method for calculations allowing engineer to calculate in the first step, with a short simple program, crucial points on the error characteristics of every selected pair of PRTs. User can than choose a best application range for temperature and for temperature difference range and calculate values of errors in those ranges.