UNCERTAINTY ASSESSMENT OF RESISTANCE THERMOMETRY BRIDGES

摘要

Despite the importance of resistance bridges in thermometry, an accurate assessment of their uncertainty has not been investigated much. Among various uncertainty components, nonlinearity and ratio error have been of particular interest, and a Hamon-type resistance network known to be RBC (resistance bridge calibrator) is widely used to measure those uncertainties. However, due to finite temperature coefficients of base resistors in the RBC, the evaluated uncertainty of the resistance bridges under normal operating environment is in doubt. In this work, to accurately evaluate the uncertainty of the resistance thermometry bridge, an air medium thermostatted chamber was devised, and the nonlinearity and ratio error of a resistance bridge at KRISS (ASL F900) were assessed. Along with this, repeatability and AC quadrature/frequency dependence of the resistance bridge were evaluated and total combined uncertainty of the resistance bridge at KRISS was finally assessed.