Computer-Controlled Inductive Bridge Standards for Calibrating AC Resistance Thermometry Bridges at Low Frequencies

This paper describes the setup and calibration of inductive bridge standards which realize selected voltage ratios—in particular, ratios between 0.1 and 1.3—at frequencies of a few tens of hertz with uncertainties from $1 \cdot 10^{-8}$ to $2 \cdot 10^{-8} (k = 2)$ . With these bridge standards, ac thermometry bridges can be calibrated with the lowest possible uncertainties either manually or using computer control.