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

A comparison of the 10 V Josephson array voltage standard of the Bureau International des Poids et Mesures (BIPM) with that of the Centro Nacional de Metrolog a (CENAM), Mexico, was made in September 2011. For this comparison, both options of the BIPM. EM-K10. b comparison protocol were applied (A and B). Option B required the BIPM to provide a reference voltage for measurement by the CENAM using its Josephson standard with its own measuring device. Option A required the CENAM to provide a reference voltage for measurement by the BIPM using its analogue detector and associated measurement loop. In both cases the BIPM and CENAM arrays were kept floating from ground. The final results observed were in excellent agreement with the combined relative standard uncertainty of 6.7 parts in 1011 for the nominal voltage of 10 V.