engleski

Use of precise digital voltmeters for impedance measurements

The traceability chain of the Primary Electromagnetic Laboratory (PEL) is presented, and the place of the resistance standard of 100 Mohm is analysed in details, as well as its construction and characteristics. Its one hundred 1-Mohm elements in parallel connection forms the 10-kohm value, and can be easily compared to the reference 10 kohm standard of PEL ; in that way its long-term drift was found to be 0, 067 ppm/day (ppm means parts per million). Furthermore, the method of comparison of 100 Mohm resistance standard by means of 100 pF capacitance standard and high-resolution digital voltmeters (DVs) is analysed, where DVs measure ac voltage of frequency close to 16 Hz in dcv range, and the mean value of one-third cycle is measured. It was found that the voltage ratio could be stable within the limits of 0, 1 ppm when the additional frequency stabilization of the ac calibrator is used.

resistance standard ; capacitance standard ; digital voltmeter ; ac voltage

nije evidentirano