标准铂铑10-铂热电偶热电势约束公式探讨

铂铑10-铂热电偶可以通过3个固定点的热电势与温度之间的关系反映其特性。在ITPS-68温标中,铂铑10-铂热电偶作为温标内插仪器,其3个固定点热电势必须满足一定的约束公式。介绍了从其约束公式推导出现行检定规程使用的3个不同的温度固定点的新约束公式,以规范标准铂铑10-铂热电偶的热电特性;通过对大量源于中国计量科学研究院热电偶校准实验室的标准热电偶的实际数据的计算,验证了新约束公式的有效性。新公式在锌固定点的不合格检出率从0% 提升到3%左右。

The Research on the Constraint Formulas of EMFs as a Standard Pt-10% Rh/Pt Thermocouple

The characteristics of Pt-10% Rh/Pt thermocouple on temperature versus EMFs were described with the calibration results on three fixed point temperatures. In ITPS-68 temperature scale, Pt-10% Rh/Pt thermocouple was selected as interpolation equipment, and its three fixed point EMFs should be restrained to meet the certain formulas. The new constraint formulas on three different fixed point temperatures were derivable from traditional requirement in IPTS-68 to regulate the standard Pt-10% Rh/Pt thermocouple characteristics, and were verified to be efficient by the original data of the great amount of thermocouples from the calibration service laboratory of National Institute of Metrology. The rejection ratio of standard thermocouple at Zn fixed point was slightly raised from 0% to about 3% when the new constraint formulas were applied.