On October 29, 2018, the Vaia storm caused damage to the 380 kV Pradella - Sils im Domleschg power line. Gale-force winds with estimated peak speeds of around 200 km/h brought down four support masts on the 2315-meter-high Albulapass. Meteotest has analyzed the incident.
The temperature at the pass was around freezing point at the time of damage. No ice accumulation was observed on the conductor cables. As there is no weather station at the Albulapass and in its vicinity, no reliable information can be provided on the effective wind speeds at the site and at the time of the damage. Swissgrid is interested in the impact of strong winds on the pylons in order to adequately dimension future installations for extreme events and commissioned Meteotest to analyze the event.
First, Meteotest carried out a synoptic analysis of the event to understand why this particular storm was able to cause such pronounced damage. Then, Meteotest simulated the event with a high-resolution turbulence model and quantified the wind load on the masts and the transmission line. Findings from these results are incorporated into the calculations of the wind loads for future power lines.