NIM新一代二端对电容电桥装置

基于一种交流电桥自动辅助平衡方法,中国计量科学研究院(NIM)研制了新一代二端对电容电桥装置。电桥采用固定比率的感应耦合比率臂电桥,通过复用比率,用单一电桥即实现了计算电容过渡和电容10:1传递;采用一种改进的靴带法实现电桥感应比率臂比率的精确校验。该装置用于电容单位的量值复现和标准电容器的高准度量值传递。利用新一代二端对电容电桥装置,可从计算电容装置复现1 pF电容值,并实现电容 1~100 pF的十进制量值传递,电容量值传递相对标准不确定度可达5×10^-9(1592 Hz)。采用该电桥参加了10 pF和100 pF电容国际关键比对(CCEM.K4-2017),中国比对成绩优异,数据均非常接近关键比对参考值(KCRV),其中100 pF的结果最接近KCRV,与KCRV取得了很好的一致性,从而获得国际互认。

The New Two Terminal Pair Capacitance Bridge at NIM

An improved two terminal-pair coaxial AC bridge with auto source balance was constructed at NIM for high precision capacitance measurement.The errors introduced by auto source balance in the bridge are at negligible level.The bridge can disseminate the calculable capacitance to 1 pF,and transmit capacitance from 1 pF to 100 pF.An improved bootstrap method to calibrate the IVD ratios was adopted.A minimum standard uncertainty 5×10^-9 was achieved at 1592 Hz.The two terminal-pair capacitance bridge was applied to participate in the international key comparison of 10 pF and 100 pF capacitance standards,the comparison results showed that NIM s comparison results for 10 pF and 100 pF achieved a very good agreement with the KCRVs(key comparison recommended value),which obtained the international mutual recognition.