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The work to repair the four bent pylons on the Albula Pass lines, which were damaged by Storm Vaia at the end of October, will commence in spring 2019. Clearance work on the site is completed.
On the night of Tuesday, 30 October 2018, Storm Vaia caused four overhead line pylons on the Albula Pass (Graubünden) to bend or collapse. Since then, the two affected 380 kV lines, Filisur – Robbia and Pradella – Robbia – Sils, have been out of service. The section of the 380 kV Pradella – Robbia – Sils line between Pradella and Robbia was brought back into operation on 31 October.
The clearing work, including the demolition of the conductors and the damaged pylons, is completed. The faulty pylon profiles and the conductors have been retrieved from the high Alpine surroundings with the help of a heavy-load helicopter.
Repairs to start in May 2019
The work to repair the two faulty 380 kV lines will commence in May 2019. This work will take two to three months. It is planned that the lines will be brought back into system operation at the end of July 2019.
For a number of reasons, Swissgrid has decided against installing a provisional solution using emergency pylons, largely on account of safety concerns. At Swissgrid, safety comes first. Erecting emergency pylons in high mountainous areas in winter poses many risks for people and materials. In addition, the time window for installing such a solution before the first major snowfall would be very short. From this point on, the risks and technical requirements involved in installing and operating a provisional line increase considerably due to the weather conditions (snow and ice load, risk of avalanches) and works would need to be suspended immediately.
Security of supply guaranteed – transit capacity towards Italy reduced
The outage of the two 380 kV lines has no impact on the security of supply in Switzerland or in the affected regions in Graubünden. N-1 grid security in the transition system is guaranteed.
The unplanned outage of the two lines since the storm has limited the transit capacity towards Italy. The monthly net transfer capacity (NTC) towards Italy has been reduced by 900 MW due to the outage of the Filisur – Robbia line. Measures are being taken in close consultation with the Italian grid operator TERNA and other neighbouring transmission system operators and will remain in place until the repair work has been concluded.