Interpolating AC-DC transfer differences for an AC-DC voltage transfer standard

The AC-DC difference of an AC-DC transfer standard varies with its input voltage and ac frequencies. Its calibration may not necessarily cover all the voltage-frequency points for their possible uses in practice. This results in situations when there is no reference value to use such a transfer standard for calibrations at some voltage-frequency points. This paper analyses the principle structure of a transfer standard, shows the possibility of interpolating points based on calibrated ones, and presents the interpolation results performed in the National Metrology Centre (NMC).