Report of a Multilateral Accurate Measurement Comparison on a High-Precision Multimeter to Evaluate the Traceability Transfer from INRIM in the Field of Low-Frequency Electrical Quantities

As the calibration activity of modern electrical secondary laboratories operating in the five low-frequency quantities is carried out by means of high precision digital multimeters (DMMs), it is of fundamental importance their correct technical surveillance through suitable inter-laboratory comparisons (ILCs). The laboratory for calibration of multifunction electrical instruments of the National Institute of Metrology Research (INRIM-Lab) provides bilateral and multilateral ILCs involving high precision DMMs to check the measurement capabilities of electrical laboratories. In particular, this paper deals with the last multilateral ILC that INRIM-LAB provided and carried out as reference measurements provider to which took part twelve Italian accredited laboratories divided in two loops. The In the ILC was involved a high precision 8.5 digit high precision DMM to be verified in a grid of about forty measurement points. The 2 relative uncertainties of the INRIM-LAB calibrations ranged from 1.6106 to 1.5104 while those of the laboratories ranged from 2.0106 to 2.2103. The ILC had satisfactory results confirming the correctness of both the dissemination from INRIM and the accreditation process by the Italian accreditation body for calibration laboratories.