This document studies the deterioration mechanisms of insulating materials used in the electrical sector, with reference to the analysis of the behaviour of polymers and resins. The presence of internal defects in the materials can in fact compromise, with catastrophic results, the dielectric strength of the insulating systems of the components of the electrical systems: the partial discharges generated in the presence of such defects can in fact progressively erode the dielectric materials, up to their perforation. In the first part of the document, the possibility of using a completely passive sensor for defect localization is therefore studied using numerical analysis methods.

Subsequently, it is shown how localization algorithms can predict the progression of partial discharge events with high accuracy, thus allowing the monitoring of their evolution. The model of the chemical network of the resins commonly used for electrical insulation was also built. This model was used to analyse how the impact of ionic species, accelerated by the electric field, can contribute to the modification of the surface of the material, thus affecting its dielectric strength.

At an experimental level, a plasma aging campaign was conducted on resin samples. This campaign made it possible to analyse the effect of the plasma on the structure of the resin in two different types of atmospheres, using spectroscopic techniques. Finally, a campaign of thermal aging cycles was carried out on a resin-insulated transformer taken from operation.

These tests have allowed us to collect useful data for understanding the thermal effects on the structure of the resin and will constitute the starting point for the further development of temperature-dependent chemical models.

The Report is available on the Italian site