Research on the Technology of Calibrating millivolt AC voltage Source

An accurate calibration method of millivolt AC voltage source based on cascaded voltage divider and AC-DC transfer technology is proposed in this paper. The cascaded voltage divider and 792A AC-DC transfer standard are adopted to trace the measured millivolt AC voltage to the known national AC voltage standard. By using the substitution measurement method and choosing the combination of different voltage proportion and different range of 792A, the AC voltage in the range of 10 mV~200 mV at the frequency of 55 Hz~5 kHz is accurately calibrated. Results show that the relative error of any measured millivolt AC voltage is within ±40 μV/V, and the expanded uncertainty is better than 130 μV/V, which shows that this method can meet the traceability requirements of millivolt AC voltage source.