Investigation of the influence of measurement duration on results of resistance bridge ratio error assessment

The realization and dissemination of the International Temperature Scale (ITS-90) relies greatly on the performance of resistance ratio bridges that are used for the precise measurement of electrical resistances of standard platinum resistance thermometers (SPRTs). Characterization of resistance bridges has been made significantly easier since the invention of resistance bridge calibrators (RBCs), which can be used for the determination of ratio error and linearity of a resistance ratio bridge. Even though there has been a lot of research on the operation and performance of RBCs, the influences of measurement time on the results of resistance ratio bridge characterizations have not been investigated in much detail yet. Minimizing measurement time for each separate resistance ratio leads to a reduction of the overall duration of the characterization process, which could easily exceed 10 hours. It could also lead to the reduction of uncertainty of bridge characterization since its results rely greatly on the stability of the RBC's resistances as well as the resistance of the standard resistor connected to the bridge during the entire characterization process. In this research, a new method is proposed for the determination of the minimum delay required between changing the RBC resistance and start taking the readings, as well as for the determination of a minimum number of readings that should be taken by resistance ratio bridge for obtaining representative overall characterization results.