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Austria – EQOS Energie concludes replacement of straining clamps in high mountain area

On behalf of Austrian Power Grid AG (APG for short), EQOS Energie has exchanged the straining clamps on a total of 25 corner masts. The 380-kV Lienz-Tauern line goes over the Alps from Matreiertauernhaus in the Tauern mountains to Lake Hintersee in Mittersill. The greatest challenges during the project work were the altitude difference of the mast locations and the associated weather conditions as well as the inaccessibility of some of the mast locations. The work for APG was successfully concluded at the end of September.

The 380-kV line was constructed in 1977. The straining clamps to be exchanged were from the same time period and showed the corresponding wear and tear, which was to be permanently eliminated. Overall, the work was performed over a route length of about 10 kilometres. Since the masts were located in a high mountain region, i. e. on steep terrain, most of them were hard to reach. During the six-week construction period, a helicopter was used eight times in order to transport an average of 20 fitters, their tools and personal protective gear to the respective sites. For 20 locations, materials also had to be transported by helicopter.

On the Tyrolean side, only a steep mountain road led up to an altitude of 2,350 metres. Fitters were only able to travel on this road with a special all-terrain vehicle with reduction gear units. The weather negatively impacted the work of the fitters on more than half of the work days. The Upper Tauern mountain range is a meteorological divide in which it is rare that both sides of the valleys exhibit the same weather. At the start of September, some parts already had half a metre of fresh snow, which made the work extremely difficult. Based on some of the strong wind speeds at altitude, which reached up to 100 to 120 kilometres per hour, even the helicopter had a hard time reaching the somewhat inaccessible mast sites.

Overview of the services

  • Exchange of straining clamps on 25 corner masts
  • Conductor: vertical Al/St 680/85 system with sigma 0 of 7.5 daN/mm²/6,8 daN/mm²
  • Maximum occurring traction is 178 kN per cable
  • Highest mast location: 2,500 m above sea level/lowest mast location: 1,300 m above sea level
  • For 20 masts, the materials were transported by helicopter

Fact box

Austrian Power Grid AG

Execution Period:
August 2017 to September 2017

Erection site:
380-kV Lienz-Tauern line, Austria