Comparison of the Josephson Voltage Standards of the NIM and the BIPM (part of the ongoing BIPM key comparison BIPM.EM-K10.b)

A comparison of the Josephson array voltage standards of the Bureau International des Poids et Mesures (BIPM) and the National Metrology Institute (NIM), Beijing, P.R China, was carried out in November 2013 at the level of 10 V. For this exercise, options A and B of the BIPM.EM-K10.b comparison protocol were applied. Option B required the BIPM to provide a reference voltage for measurement by NIM using its Josephson standard with its own measuring device. Option A required NIM to provide a reference voltage for measurement by the BIPM using its analogue detector and associated measurement loop. In both cases the BIPM array was kept floating from ground. The final results were in good agreement within the combined relative standard uncertainty of 9.2 parts in 10(11) for the nominal voltage of 10 V.