Improving uncertainty of strain gauge bridge standards

The article proposes a procedure for calibration of strain gauge bridge standards with improved relative calibration uncertainty. In contrast to a typical calibration with voltage ratio standards or comparison calibration with other bridge standards, the proposed procedure uses a calibrated reference bridge amplifier, additionally evaluated using combinatorial calibration technique to improve its calibration uncertainty. The resulting uncertainty of ratio steps referenced to zero ratio step is lower than the traditional uncertainty achieved through direct independent traceability to mVV⁻¹ ratio values. The proposed procedure enables direct application of the calibrated bridge standard values with low relative uncertainty for calibration of bridge amplifiers, without the need for additional combinatorial evaluation of each individual bridge amplifier. (paper)