Inter-laboratories comparison at 100 GΩ and 1 TΩ level to evaluate the traceability transfer from INRIM in the field of high dc resistance

A National inter-laboratories comparison of dc resistance at 100 GΩ and 1 TΩ among the National Institute of Metrological Research (INRIM) and eight Secondary Electrical Calibration Laboratories was carried out in 2010. All the involved Laboratories made their measurements with a method based on a Multifunction Calibrator (MFC) and on a digital multimeter (DMM), both used in their dc voltage function. These and other Secondary Electrical Laboratories are traceable to National Standards by means of the calibration at INRIM of a complete set of primary standards or, alternatively, by means of the calibration of a high accuracy DMM or of a Multifunction Transfer Standard (MTS) or of few primary standards. All the relative differences between each Laboratory’s value and its reference value obtained in the comparison were within their relative expanded uncertainties. This result showed that the traceability transfer methods from INRIM to Electrical Secondary Laboratories lead to satisfactory results in the field of high dc resistance.