Temperature-Measurement Errors with Capsule-Type Resistance Thermometers

摘要

Inspired by a lot of discussions within the temperature-measurement community on unresolved discrepancies occurring in conjunction with the application of capsule-type resistance thermometers, PTB has performed a detailed theoretical and experimental treatment of this problem. The focus of this work lies on the investigation of errors caused by the heat conduction via the measuring electrical leads that causes a temperature difference between the sensor element and the body, the temperature of which has to be measured. In analogy to electrical networks, a model connecting thermal resistances and heat flows has been established to describe the thermal conditions within the thermometer. The model leads to the definition of new thermometer parameters, called thermal resistance and reduction factor, that have to be determined either by dedicated experiments or theoretical simulations.