Portable DC Voltage and Resistance Reference with Switching Unit for Calibration of Electrical Precision Multifunction Instruments

A portable temperature controlled DC Voltage and DC Resistance Reference with Switching Unit (RSU) has been developed at National Institute of Metrological Research (INRIM) to calibrate multifunction electrical instruments involving 10 V, a $\pmb{1 \Omega}$ and a $\pmb{10 \mathrm{k}\Omega}$ Standards. The resistors are made with two resistors nets while the 10 V is a low noise-drift INRIM-projected circuit. Preliminary measurement over one-month period shows standards uncertainties span from $\pmb{3.0\times 10^{-7}}$ to $\pmb{6.4\times 10^{-7},}$ suitable for artifact calibration. With a real clock calendar, the RSU can show both the RSU Standards calibration values and updated ones between two calibrations according to an internal algorithm.