Wet-snow sleeve accretion on conductors is the main cause of failure on the power grid that distribution and transmission operators have to face. RSE has developed the WOLF (Wet-snow Overload aLert and Forecast), a forecasting system that can provide for the 72 hours ahead the snow load on the entire high-voltage power grid, and the estimated anti-icing current for the expected weather conditions. In parallel, an experimental activity was initiated with the establishment of the WILD (Wet-snow Ice Laboratory Detection) station for the study and monitoring of build-up on conductors. The station ‘tuned’ the parameters of the growth model and verified the thermal model of anti-icing under snowfall conditions. Some measurements of LWC (Liquid Water Content) in snow loads were also acquired at the station. The LWC data can be useful in analyzing the growth and detachment phase of the build-up.

A series of tests comparing conductors coated with different ice-phobic materials are being conducted at the station. Ice-phobic coatings are of great interest to TERNA, and these tests offer the possibility of selecting coatings for operational experimentation on high-voltage lines in areas exposed to the risk of wet snowfall. An operational trial is currently underway with TERNA in Veneto, Italy, on a 132kV line on which three spans treated with ice-phobic coatings have been installed and a fourth serves as a reference. The performance of the coatings is evaluated qualitatively by analyzing images taken by two cameras.

The ongoing activities also aim to measure snow load on MV lines in collaboration with e-distribuzione at three climatically different sites, and with spans equipped with different diameter conductors. The aims are to validate the build-up model on real spans, to compare the loads created on conductors of different diameters, and to integrate the measurements from the lines with the WOLF forecasting system. The measurements of loads on the lines will be used as part of the work to revise the map of snow and ice overloads over Italy for the NNA linked to the CEI-EN-50341-2-13 standard on the mechanical design of overhead lines.