Traceability of Bridge Amplifiers in Tared Measurement Applications
A. Brüge
Abstract:
The influence of the primary voltage ratio standard uncertainty on strain gauge measurements, especially at secondary levels like torque wrench calibration, is discussed. A method is presented to overcome its 1/x behaviour, which affects the uncertainty budget at lower ratios for the usual point-by-point transfer of uncertainty. Monte Carlo simulations of fitted correction values reduce the relative expanded contribution of the traceability uncertainty to less than 1 · 10-5 for tared measurements with bridge amplifiers in comparison to five times more for point-by-point traceability. Considering typical further uncertainty contributions, a tared measurement of voltage ratios is possible with a combined relative expanded uncertainty of less than 1.8 · 10-5.
Keywords:
voltage ratio, traceability, bridge amplifier, uncertainty, linearity
