高精密测温电桥的标定与评估

Calibration and Evaluation on High Precision Thermometry Bridge

使用RTU和RBC两种精密仪器对中国计量科学研究院中温基准实验室的F、900高精密测温电桥进行了标定和评估，分析了不同工作频率、不同输出电流在长杆标准铂电阻温度计测温范围内对测量精度的影响。结果表明：电桥在不同的工作频率下精度的差异比较明显。工作频率为25Hz时，使用RTU和RBC进行标定的最大测量偏差分别约为0．01mK和0．06mK；工作频率为75Hz时，使用RTU和RBC进行标定的最大测量偏差约为0．08mK和0．2mK，且相比出厂时有了较大的漂移。电桥在不同的输出电流下精度的差异非常小，在15μK以内。采用RTU及RBC对F900测温电桥评价的结果之间相互印证，该结果对中温固定点基准复现过程的不确定度评定提供了数据支撑。

The RTU and RBC were used to calibrate and evaluate the Fg00 high precision thermometry bridge in the middle temperature primary standard laboratory of the National Institute of Metrology, and the effect of different frequency and output current on its measurement accuracy was analyzed in the temperature range of long-stem standard platinum resistance thermometer. The results show that the accuracy is obvious difference when the bridge works in different frequency. When the frequency is 25 Hz, the maximum measurement deviations in the calibration of RTU and RBC are about 0. 01 mK and 0.06 mK. When the frequency is 75 Hz, the maximum measurement deviations of the calibration are about 0.08 mK and 0.2 mK, and it has made significant drift compared to that of the factory. Differences in accuracy is very small when the bridge works at different output current, less than 15 μK. The results using RTU and RBC to calibrate F900 can confirm each other, and provide data to the uncertainty evaluation in reproduction process of the fixed-point temperature reference.