by Flavio Galliana & Alessio Pollarolo
An automated temperature-controlled DC Voltage-DC Resistance Multiple Standard (VRMS) for artifact calibration of high end calibrators and multimeters was developed by Measurements International (MI) with the support of the Istituto Nazionale di Ricerca Metrologica (INRiM). The VRMS consists of a 10 V, a 1 Ω, and a 10 kΩ standards selectable via a low thermal scanner. The two resistors are high-stability MI standards while the 10 V standard is based on a low-noise circuit developed by INRIM. A smart feature of the VRMS is its internal algorithm providing updated calibration values of the VRMS standards ensuring their reliably use in the whole period between calibrations. The standards are housed in a thermal box shielding them from temperature changes. The use uncertainties of the VRMS standards are consistent with those for artifact calibration of calibrators and multimeters. The VRMS standards can also act as laboratory references or traveling standards for interlaboratory comparisons (ILCs). MI is currently commercializing the VRMS as 1330A Artifact Transfer Standard.
