The research activity covers a wide range of topics in the field of electromagnetism, from computational modelling to the development of references and measurement techniques of electromagnetic fields, high voltages and high currents.

The increasing interest in smart sensors and actuators involves the development of new techniques for material characterization and measurement of device performances. This interest is confirmed by the two-year Research Project "Magnetostrictive materials for the active control of vibrations", financed by the Regione Piemonte and started in 2006. Currently, a Finite Element electromagnetic model of a complete device has been developed and validated up to some hundreds of hertz. The future research targets are the dynamic magnetoelastic characterisation of the material and the integration into the numerical code of a sophisticated magnetostriction model.

The mathematical homogenisation technique, able to replace a heterogeneous structure with an equivalent homogeneous one, has been employed in an efficient analysis of magnetic and pure conductive grid shields. The results have been validated by comparison with experiments developed on a specific laboratory set-up for frequencies up to 2 kHz. Further activities, in cooperation with electric companies, have been carried out to mitigate, through metallic laminations, the magnetic field produced by a three-phase 500 A power line below the induction level of 200 nT and for the magnetic shielding of a 150 MVA power station.

The characterisation of the fully anechoic chamber has been completed from 500 MHz to 3 GHz through the accurate gain evaluation of the standard horns and open-ended guides used to generate the reference field. In cooperation with the Politecnico di Torino and the Agenzia Regionale per la Protezione dell'Ambiente (ARPA), the behaviour of different commercial isotropic field meters in the presence of wideband digital signals has been analysed within the chamber. A first investigation has been performed by varying the parameters associated with the incident field (power level, frequency, bandwidth and modulation), in the case of Wi-Fi and Wi-Max signals.
A numerical evaluation of the electric field distribution in TEM cells supplied at low frequency has been started by using a 3-D Boundary Element Method. The analysis has been performed both in the case of an empty cell and by considering the effect of the dielectric element used to support the field probe during calibration. Comparison between experimental and simulated field distributions has been carried out on the INRIM TEM cell.
A Helmholtz coil-based system, for the generation of reference magnetic fields characterised by a distorted waveform with frequency content up to 100 kHz, has been set up to evaluate the response of new generation field meters, implementing standardised weighting functions.

A reference measuring system, suitable for voltage measurements in low voltage short-circuit tests, has been realised and tested. This system consists of four voltage transducers, a transmission system, optically-coupled insulation amplifiers and a multi-channel A/D board. The voltage transducers are mixed resistive-capacitive voltage dividers with 3 kV maximum input voltage and interchangeable low voltage arms. The choice of high stability ceramic capacitors and film resistors has allowed the reduction of divider ratio thermal drift at less than 50 ppm/°C. Adjusting the matching between high voltage and low voltage arms, a bandwidth higher than 700 kHz has been obtained, enabling the use of the dividers in Transient Recovery Voltage (TRV) measurements.

An innovative cell for electrolytic conductivity measurements has been designed with the aid of a 3-D numerical model, based on the Boundary Element Method. The cell, developed in cooperation with the Electrical Metrology Section, has an electrode-matrix geometry, which guarantees the extension of measurements to a wide range of electrolytic conductivity values. This versatility is due to the multi-electrode structure, which enables the modification of the cell constant, simply by varying the number of active electrodes.