Power line crossing of the Strait of Messina
The power line crossing of the Strait of Messina serves to connect the power grid from Sicily to that of the Italian mainland . It has existed since 1955 and was implemented as an overhead line crossing by 1994 , the masts of which are still standing today.
Overhead line crossing
Crossing masts
In 1955, a high-voltage line (up to 1971 with a voltage of 150 kV, from then 220 kV) from the Calabrian substation Scilla ( Lage ) to the Sicilian substation Messina-Santo ( Lage ) on the Strait of Messina in Torre Faro (Sicily) and Cannitello was built di Villa San Giovanni (Calabria) each built a 224 m high high-voltage pylon designed as a free-standing steel lattice tower. Each of these masts stands on a cruciform 8 m (26 ft) high foundation, resulting in a total height of 232 m, and carries a crossbeam at a height of 212 m (696 ft) to accommodate four conductor cables. There was space for two more conductor cables at the V-shaped tip on which the earth cables were also mounted. In contrast to conventional masts, the corner posts of the masts were arranged diagonally to the direction of the line. This arrangement was later adopted at Elbe crossing 1 in Germany. The masts of the overhead line crossing of the Strait of Messina were the highest overhead line masts in the world until the completion of Elbe crossing 2 .
The duration and amplitude of the natural oscillation of the Messina overhead line masts were determined in a very unusual way after their completion, by detonating three rockets with 9,800 kN thrust at their tip.
The overhead line crossing went into operation as a single-system 150 kV line with four conductor cables, one of which served as a reserve. In 1971 two more conductor cables were installed and the operating voltage increased to 220 kV, resulting in a transmission capacity of 300 MVA.
Single ropes with 45 mm² aluminum cross-section and 305 mm² steel cross-section, so-called AlSt-45/305 ropes, were used as conductor cables for both systems. The lowest height of the conductors above the Strait of Messina was 70 m. In order to achieve this with a span of 3646 meters, a tensile stress of 608 N / mm² was necessary in the conductor cables.
In the 1980s, the transmission capacity of this system was no longer sufficient. It was not possible to increase the transmission capacity by using bundled conductors, because in the long span they have a greater tendency to wind-induced vibrations than single conductors, which can lead to short circuits. Ropes with better conductivity were also out of the question, as they cannot withstand the required tensile stress. Therefore in 1985 a 380 kV submarine cable with 1000 MW transmission capacity was laid through the Strait of Messina.
The overhead line crossing was shut down in 1993 and a year later the conductor cables were dismantled, after which the masts were placed under monument protection and used as a meteorological measuring station, for exercise at height rescues and as antenna carriers.
Since 2006 it has been possible to climb the mast on the Sicilian side via 1250 steps.
Switching stations
In contrast to other comparable overhead line crossings, switching stations were built at both ends of the span, the structures of which are still there today. The ropes of the overhead line crossing were - in contrast to practically all other overhead line crossings of wide waterways - tensioned like the overhead line of a railway with a weight tensioning device at one end. The rigid end of the overhead line crossing was in the station near Cannitello in Calabria, the tensioning device was housed at the station in Sicily in a building with two towers that still stands today.
Feeder line
The power line from the Scilla substation to the former switching station in Cannitello still exists, but is unused. The line from the Torre Faro switching station to the Messina-Santo substation has now been completely dismantled.
Submarine cable crossing
The submarine cable laid in 1994 to replace the overhead line crossing is part of the single-system 380 kV line from the Rizziconi substation in Calabria to the Sorgente substation. It has a transmission capacity of 1000 MW and begins at the end of the overhead line coming from the Rizziconi substation, south of Villa San Giovanni in Calabria, and reaches Sicily in the urban area of Messina. This runs through it as an underground cable before it ends in the north of Messina, where the overhead line to the Sorgente substation begins.
The cable consists of four conductors, with the fourth conductor serving as a reserve.
Planned second 380 kV cable
Another 380 kV line was built between Sorgente and Rizziconi by 2016. It has a length of 105 km with a maximum transmission capacity of 2000 MW. The submarine cable section is 38 km long.
Individual evidence
- ^ Tower structures, Bauverlag GmbH, Wiesbaden, 1966
- ↑ Francesco Pagano: Il Pilone de Torre Faro. August 20, 2007, accessed April 25, 2010 (Italian).
- ↑ Peppe Caridi: Elettrodotto "Sorgente-Rizziconi" il Ponte sullo Stretto energetico ecco perchè è un'opera straordinaria . In: Stretto Web . May 26, 2016 ( online ).
- ^ Green light for the new "Electricity Bridge" across the Strait of Messina. Archived from the original on September 11, 2012 ; accessed on November 15, 2016 .
- ↑ Il nuovo elettrodotto “Sorgente-Rizziconi” tra Sicilia e Calabria (schematic map)
Map with all coordinates: