Elering invests 14 million euros into new sea cables in Suur and Väike Väin straits

Elering has signed the companies chosen in two public procurements, Merko Infra and Connect, to contracts for the construction of new electrical submarine cables in the Suur and Väike Vain straits. Together, the Rõuste-Tusti submarine cable, which will link the mainland and Muhu Island, and the submarine cable across Väike Väin strait will cost 14.4 million euros.

“The submarine cable to be established across Väike Väin under contract signed today will significantly increase the security of supply for Saaremaa and Hiiumaa islands, as to this point it has been completely reliant on the overhead lines across the strait. In addition, the submarine cable will enable the number of high-voltage line conductors on the causeway to be reduced by half and the remaining overhead line can be made better visible to birds,” said Taavi Veskimägi, the chairman of Elering’s management board.

"Over the last years, we have built the Suur Väin submarine cable, and renovated Võiküla and Leisi substations. At the moment, the acceptance from the builder of the Orissaare substation – in principle built from ground up – is in the home stretch. In the years ahead, we will also renovate the Sikassaare substation on the outskirts of Kuressaare and, in order to increase security of supply, will place the Võiküla-Orissaare and Tusti-Orissaare overhead lines across Muhu Island on to separate pylons. The last of these investments along with the cable across the Väike Väin strait will ensure that the islands get two independent electrical connections – there will be a reliable power supply loop,“ said Veskimägi in describing Elering’s largest investments into the islands’ power system.

With the recently concluded contract, two old and depreciated 35-kilovolt submarine cables between Rõuste and Tusti substations in the Suur Väin Strait will be replaced with a single new 110-kilovolt submarine cable. The total length of the Suur Väin cable is close to 11 kilometres, of which 9.7 km is the submarine part. To connect the new cable, a new cell at Rõuste substation will be established. The contractual cost of the works will be approximately 9 million euros.

The new 110-kilovolt cable line across Väike Väin from Muhu Island to the new Orissaare substation is 6.7 kilometres in length, of which 4.7 km runs along the seabed. The cost of the Väike Väin cable is close to 5.4 million euros.

The capacity of both of the straits cables is 520 amperes. In the submarine cable, three phases are united in one cable. The diameter of the cable is 190 millimetres, and the weight is 67 kilograms per metre. The submarine cables will be installed into the sea as a single long cable – without extension couplings. Together with the new cable, a fibre-optic communication cable will also be installed in the sea. In both straits, the cable will be embedded in the seabed to reduce the risk of damage by anchors, ridge ice or other outside factors.

The cable installation works are planned to begin in spring 2020 and will be completed by that autumn.

The first modern 110-kilovolt submarine cable was established by Elering between mainland and Muhu Island in 2015. Since it was completed, this cable has borne most of the burden in supplying Muhu, Saaremaa and Hiiumaa islands with electricity.