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At the National Institute of Metrological Research (INRIM) a measuring setup able to vary, accurately and in a selective way, the temperature, humidity and pressure to detect eventual hysteretic phenomena and to evaluate their effects on electrical standards as high precision standard resistors and Zener-diode based DC Voltage standards. Main element of the setup is a pressure-tight case housing the standards and acting the stresses due to the desired parameters. By means of pressure-tight-connectors, the standards under test are connected to the measuring instruments, while the climatic conditions are acquired through inner and external sensors. Humidity is controlled by means of two conditioning containers filled respectively with water and silica-gel, which regulate the air-moisture percentage the case in a range of 10-90%. A pumping system establishes the pressure in the case from 600 hPa to 1400 hPa. The characterization vs. humidity and pressure is made at constant temperature by means of a commercial air-bath acting from 15 and 45 ° C. Preliminary results have been obtained for pressure dependence of commercial 100 Ω resistors and of an INRIM-developed 10 V Zener-diode based DC Voltage standard.

At the National Institute of Metrological Research (INRIM) an automatable precision DC voltage fixed-ratios divider allowing the division ratios of DC Voltages from 10:1 to 107:1. It can be quickly calibrated when necessary and involved in traceability transfer. Its resistors are selected bulk metal foils ones connected in series in four terminal configuration whose values are 90 kΩ, 9 kΩ, 900 Ω, 90 Ω, 9 Ω, 0.9 Ω, 90 mΩ and 10 mΩ. The main advantage of this divider is that it can be automatically calibrated with a calibrator and a digital multimeter. Its calibration starts from a10 V value. It takes advantage of the DMM linearity, in particular in the 10 V range that allows improving its calibration uncertainty. After calibration, it can be used to divide DC Voltages lower than 10 V. Preliminary evaluation of its calibration uncertainties and mid-term stabilities (a week) span respectively from 1.4×10-6 to 6.0×10-4 and from 2.4×10-7 to 4.5×10-4 for ratios from 10:1 to 107:1. This divider could be involved in the calibration of nanovoltmeters in a typical range from 10 V till down to 100 nV.

Inter-laboratory comparisons (ILCs) are an effective mean to establish the compatibility of the measurements among laboratories. As consequence they are a mean to assure confidence in the competence and in the correctness of the dissemination processes from national Standards in different countries. This paper refers on a ILC between the National Institute of Metrological Research (INRIM-Italy) and the European space research and technology Centre (ESA- ESTEC), belonging to two different countries, on DC Voltage, DC Resistance and Electrical Capacitance carried out in 2016. The comparison showed a satisfactory agreement between the results of the two Laboratories.

A temperature controlled 10 V, 1Ω and 10 kΩ transportable setup has been developed at National Institute of Metrological Research (INRIM) for the calibration and adjustment of multifunction electrical instruments as digital multimeters (DMMs) and multifunction calibrators (MFCs) and for high level inter-comparisons. The Resistance Standards are made of two 10 Ω and 100 kΩ resistors nets connected in parallel while the 10 V Standard is an ultra-low noise-drift based reference INRIM developed circuit. The project of the setup started from a previous realization revisiting it and adding a 10 V Standard. The resistors net of the 1 Ω is inserted in oil-bath along with the internal side of its connectors lowering the thermo-electromotive forces (emfs). The three Standards are further enclosed in a thermo-regulated copper enclosure and in an external aluminium case. The setup is also equipped with a high insulation switch to select the desired Standard. Preliminary results (3 h relative stabilities ranging from 5×10−8 to 7×10−8 ) and temperature coefficients are satisfactory to the scope of the realization.

A l’Institut national de recherche metrologique (INRIM) il a ete developpe un etalon de haute tension continue avec des valeurs selectionnables de 10 V a 100 V pour compenser le manque d'etalons de haut niveau de tension continue d'une valeur superieure a 10 V pour les comparaisons interlaboratoires de haut niveau. Il a ete utilise une nouvelle technique electronique de terre mobile. L'etalon developpe a un bruit inferieur et il a la stabilite egal a celle des calibrateurs de tension continue ou multifonction de haut niveau largement utilise dans les laboratoires d'etalonnage electriques; il a aussi une meilleure attitude a etre transporte pour les comparaisons interlaboratoires. Le projet est extensible jusqu'a 1000 V.