Automated comparator for AC-DC difference accurate measurements used at the BNM-LCIE

This paper describes the new automated comparator used at the BNM-LCIE for the calibration of voltage thermal converters with the best level of uncertainty. It allows to achieve A-type uncertainties of the order of a few parts in 10/sup 7/ in the frequency range from 10 Hz to 1 MHz (100 kHz for voltages above 100 V). B-type measurement uncertainty depends on the type of converters to be compared and on the applied voltage level, but generally is between a few parts in 10/sup 7/ and a few parts in 10/sup 6/.