Three main research areas are covered:

• DC electrical metrology;
• AC, RF and Microwave electrical metrology;
• Electrochemical metrology.

Specifically, it improves, maintains and disseminates the national standards of current, DC voltage, resistance, capacitance, inductance, AC-DC transfer, power, energy, high frequency quantities and electrolytic conductivity. The Section is also involved in the development of new measurement systems, takes part in and coordinates international comparisons, as an active member of the CCEM, CCQM, EUROMET and CODATA.

The step properties of HTS arrays under irradiation by microwaves at frequencies about 75 GHz have been investigated. The arrays are fabricated on substrates with grain boundaries, making it possible to realize a large number of junctions with uniform parameters.
High sensitivity techniques were adopted to evaluate step flatness and assess the accuracy of step voltage. A new method that makes use of an open resonator was implemented to irradiate the array, providing a higher voltage, thus increased accuracy in voltage standard applications.

An electrode-matrix cell prototype has been developed in collaboration with INRIM Applied Electromagnetics Section to study the electrical and current field in aqueous solutions considering different electrode configurations. Measurements in a conductivity wide range have been carried out for the geometrical constant evaluation as a function of the active electrodes and their surface area.
A set up for the electrolytic conductivity measurements of pure water has been developed with the collaboration of the pharmaceutical company Abbott. A preliminary comparison between two conductivity meters has been undertaken.

In May 2006 INRIM participated in the EUROMET.EM-S24 "Comparison of small current sources", involving 10 European laboratories. Two travelling standards (commercial current meters) have been calibrated at ±100 pA, ±10 pA, ±1 pA, and ±100 fA. The corresponding Calibration and Measurement Capabilities declarations for the MRA have been submitted to EUROMET.

Wide-band inductive dividers for accurate low AC voltage generation have been employed to consolidate the measurements of AC voltages at millivolt level up to 1 MHz and systems for compensating the capacitive load have been experimented.
Coaxial shunts of new type for currents up to 2 A have been built and the design has recently been extended to shunts for currents up to 20 A up to 100 kHz, where thermal problems are considerable.
An experimental system for generating calibrated currents and voltages both distorted and affected by known random components has been set up for power quality parameter traceability.

A method for deriving the kilogram from electrical quantities and for evaluating the Planck constant by a pendulum interacting with an electric system has been analyzed theoretically. A set-up for its functional demonstration has been designed and is now under construction.
Experiments of metal deposition and dissolution in solutions have been undertaken aimed at evaluating the feasibility of an electrochemical experiment for a precise determination of the Faraday constant.

INRIM has continued to realize, maintain and disseminate the primary standards for electromagnetic power up to 40 GHz and S-parameters from 30 kHz to 110 GHz. Main activity concerns the power standards, which are based on an improved twin type coaxial microcalorimeter and on calibration processes oriented to use thermoelectric sensors as transfer standards. Below 10 MHz a specific AC-DC thermal converter has been proposed for working around microcalorimeter low sensitivity. In the field of S-parameter measurements, new network analyzers have been introduced, allowing the range 30 kHz to 110 GHz to be covered without discontinuity.

A new coaxial quadrature bridge to perform R-C comparison at audio frequency has been developed. It will be employed in the traceability chain for the realization of the farad unit. In this new design, the number of electro- magnetic components is reduced to a minimum and all voltages and currents are generated by direct digital synthesis. A final relative accuracy of 10^-7 or better is expected. Report of EUROMET.EM-S20, "Intercomparison of a 100 mH inductance standard" (INRIM pilot lab), has been published in the BIPM KCDB. The figure shows the deviations of participants from the reference value. INRIM acts as associate organiser also in the EUROMET.EM-S28 follow-up inductance comparison.