Analysing the error of temperature difference measurement with platinum resistance thermometers

Abstract

An analysis of error in temperature difference measurement using pairs of platinum resistance thermometers (PRT) is presented. Nonlinearity of its characteristic makes procedure for calculating value of maximal error in the full range of measurements time consuming. For the range between 0 °C to 661 °C Standard EN 60751 defines the equation for PRT resistance versus temperature relation as quadratic equation and for range −200 °C to 0 °C as equation of third grade. The author has developed the method of calculation using search for extremum place in error characteristics of every thermometers pair.