B. Calibration of auto current comparator bridge
In this paper the standard and measured capacitors are all 10 nF precision capacitors. So, the 7010B current comparator bridge is always working in the state of 1:1 during the whole measuring process. Since its working current will change when the voltage rising. Therefore, firstly respectively select two groups of 5nF and 10nF precision capacitors, measure their capacitance ratio when the voltage is 500 V, then exchange the measure arm of the bridge (exchange arm method) and measure again. The data are shown in table 2 (T=20°C, RH=44%).