For several years, Italian power grids have been affected by wet snowfall phenomena, and some episodes such as those that occurred in February 2015 over Emilia and January 2017 over Abruzzo have resulted in vast and extended power outages, due to broken conductors and guard ropes overloaded by the weight of heavy sleeves.
Wet snow sleeve formation is a problem for which there is currently no single viable solution, but there is a need to diversify mitigation strategies. Among these, coatings are attracting the interest of Electrical Operators, conductor manufacturers and CIGRE, which concluded the work of WG B2.69 “Coatings for Power Network Equipment” several months ago, and led to the publishing of the Technical Brochure of the same name, in the drafting of which RSE also participated.
In this area, RSE studies, designs, and tests coatings for conductors and guard ropes under real snowfall conditions. As new coatings are developed, treated samples are placed in the field at the WILD experimental station in Vinadio (CN), built by RSE in 2013 for the purpose of studying the effects of wet snowfall on conductors. Spans, conductor clips, and insulators are tested under the same snowfall conditions, evaluating the behavior of the coatings compared to a similar untreated sample. The experimentation is also extended to the Malga Ciapela-Saviner operating line, in collaboration with Terna, at which three treated guard rope spans (two of which have RSE-designed coatings) are compared for several winters and the effects compared to an untreated reference span.
Results of the winter 2020-2021 experimentation of different coatings on small and medium-sized samples at WILD are presented: they show that the combination of SIVO treatment and small snow rings validates the choice of combining chemical and mechanical mitigation, suggesting an operational line trial. As for Malga Ciapela, the SIVO-based and ALK-based treatments continue to provide decent mitigation overall, and in addition to the results of the last winter campaign, the results of the two previous campaigns are also compared to assess possible aging of the chemical treatments.
The experimentation initiated between 2018 and 2019 of LoraWan-type IoT devices on HV and MV spans in collaboration with Terna and e-distribuzione, and intended to evaluate the ability of this technology in detecting sleeve formations on conductors, has continued reliably.