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Rapporto RSE 17006882

Characterization and verification of hydrophobic and ice-phobic conductors

Passive mitigation solutions based on ice-phobic coatings for conductors are meeting the interest of research and electrical operators. RSE is addressing this topic since 2015 with a multidisciplinary research approach, through the study and development of ice-phobic treatments and field tests at the WILD station in Vinadio (CN). The report analyzes in detail the behaviour of various sample of conductors coated with ice-phobic treatments in different snow conditions.

The wet snowfall events that have affected the national electricity grid in recent years have caused wideelectrical blackout situations due to the sleeves, with high values of energy not supplied andconsiderable structural damages. Electric operators are now aware that to manage the network in adverseweather conditions, it is necessary to use active and passive mitigation strategies that maximize theresilience of the electrical system. Passive mitigation solutions based on ice-phobic coatings forconductors are meeting the interest of research and electrical operators. RSE is facing this issue since2015 with a multidisciplinary research approach, based on studies, development of ice-phobic treatmentsand field tests at the WILD station in Vinadio (CN).

This is the approach also proposed by CIGRE withthe new WG group B2.69, Coatings for Power Network Equipment, to which RSE will participate.The activity of 2017 was oriented to the change of scale of the winter experimentation at the Vinadiostation, with the aim of moving from the test from conductor pieces to the test of thin experimentalspans of about 14 m. For this purpose, ten spans of 6.6 mm diameter conductor have been prepared, onwhich different treatments have been carried out, which have seen a diversification for the preliminarycleaning operations, for the heat treatments before the application of the coating and the application ofvarious coating with different methods. The winter campaign also hosted samples from the two nationalproducers of conductors, TRATOS and De Angeli, demonstrating the importance of ice-phobic coatings.The collaboration with CNR-ISTEC on coatings, which began in 2015, is going on. The tests have alsobeen conducted on samples of rigid conductors treated by De Angeli and RSE, and a PTFE coating wasalso added. During 2017, RSE, TERNA and TRATOS created a working group aimed at the operationaltesting of ice-phobic ground wires at the Malga Ciapela (BL) site, begun in February 2018.At the end of the winter, mostly characterized by dry snowfalls, the performance of the samples,compared to the reference, during the 24 snowfall events recorded by the Vinadio station were analyzed.

The performances were assessed on the ability of treatments to delay, inhibit or mitigate sleeveformation on conductors. In dry snow conditions, or at temperatures <0 ° C, the results show therepetitive capacity of the 31.5mm conductor treated by De Angeli to inhibit or delay sleeve formation.For wet snowfalls instead, which are critical for the electrical grid, the De Angeli’s conductor loseseffectiveness, and at the moment you can only count on mitigation due to early detachment compared tothe reference sample, that the conductor treated with PTFE seems to express better than the De Angeli’sconductor. No sleeves are formed on thin spans during dry snowfalls, while during the wet snowfallsthere is not a coating better than others. De Angeli’s span, however, shows a good mitigation effect in asingle case, intermediate between dry and wet snow, but still needs further evaluations.