EFFECTS OF VARIATION IN MEASUREMENT CHAIN ON TEMPERATURE MEASUREMENT CALIBRATION WITH RESISTANT TEMPERATURE SENSORS

Temperature is one of the most important key parameter to consider in measurement and mechanical engineering, because every measurement has to be conducted with reference to standard temperature conditions (20 °C, ISO 1). Strictly speaking, almost every measurement depends on the accuracy of the temperature measurement, which requires proper calibration. Therefore, standards list detailed criteria to fulfil temperature calibration with high precision. In fact, any calibration is only valid, if the whole measurement chain is taken into account. This would make recalibration necessary with each variation of the components in the measuring set-up (varying cable length, different measurement channel etc.), which is time-consuming or even impossible in practice. For that reason, this paper presents a practicable calibration strategy, which specifies each component individually and later combines the calibration results according to the composition of the measurement chain. This provides a fast and useful way to achieve the required accuracy of temperature measurement. The examined, exemplary measurement chain consists of an industrial platinum resistance thermometer (IPRT), cables with different lengths, an electrical amplifier and a reference temperature calibrator.