1. Suzhou Institute of Measurement and Testing Technology, Suzhou, Jiangsu 215128, China
2. National Institute ofMetrology, Beijing 100029, China
3. Chengdu University of Technology, Chengdu, Sichuan 610059, China
4. Guangzhou Institute of Measurement and Testing Technology, Guangzhou, Guangdong 510030, China
Abstract：The RTU and RBC were used to calibrate and evaluate the F900 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 25Hz, the maximum measurement deviations in the calibration of RTU and RBC are about 0.01mK and 0.06 mK. When the frequency is 75 Hz, the maximum measurement deviations of the calibration are about 0.08mK and 0.2mK, 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 15μK. 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.
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2016, Vol. 37 
