Interlaboratory Comparison in Context of Inappropriate Results of Voltage Thermal Converter Calibration

Abstract

The paper is devoted to the analysis of calibration results of thermoelectric voltage converter obtained by five participants of interlaboratory comparisons which ended in 2017. The analysis is accented on several aspects that led to inadequate deviation of results from the expected values. The attention is focused on the reasons for overestimation of measurement uncertainty reported by one of laboratories and the exceeding of the permissible value of criterion for assessing the competence of another laboratory at one observation point. Two variants of measurement schemes which were used by participants, are analyzed, main uncertainty sources are determined, uncertainty budgets are drawn up. The measurement model for a non-standardized measurement set-up is proposed, taking into account the drift of input and output signals. The logical conclusion of analysis is ascertainment of non-compliance with ISO/IEC 17025 recommendations and sufficient level lack of methodological support for these calibration laboratories.