Resistive Voltage-Ratio Standard and Measuring Circuit

This paper describes a highly stable, guarded dc voltage-ratio standard and the measuring network and techniques used to establish the values of its ratios to an accuracy of 0.2 ppm. The entire system is housed within a dry-air enclosure whose temperature is maintained at 23 ± 0.05°C. Discrete ratios from 1:1 to 1000:1 are provided, with maximum rated voltage set at 1000 volts. The design of the standard was chosen so that a redundancy of measurement could be incorporated in the system. Thus each successive ratio is measured by a substitution or "bootstrap" method and by satisfying the conditions of the series-parallel principle, the 10:1, 100:1, and 1000:1 ratios are measured by a second independent method. The design also admits additional checks on the validity of the measurements. An analysis of measurement errors and a discussion of their possible origin are included. Since the intent also was to design the ratio standard for low-frequency operation some preliminary data are included on its ac performance.