A precision setup and method for calibrating a DC voltage divider's ratios from 10 V to 1000 V

Resistive dividers are often used to calibrate DC voltage calibrators and voltmeters above 10 V, with ratio uncertainties lower than 10/sup -6/. The dividers need therefore to be calibrated with uncertainties lower than 5/spl times/10/sup -7/. A setup and method for the calibration of a resistive divider at its working voltage has been developed. The repeatability was found to be good enough to give standard deviations of the mean lower than /spl plusmn/1/spl times/10/sup -8/ in the measured ratio 1000/10. The total uncertainties were estimated to be less than /spl plusmn/1.5/spl times/10/sup -7/ (k=1) for all measured ratios.