Repairing EstLink 2 is complicated due to the location of the fault and the unique technical solution

The difficult geological conditions and the cable's unique technical solution make the repair of the submarine power cable between Estonia and Finland take time.

Reigo Kebja, a member of Elering's management board, said that in parallel with the work to determine the exact location of the fault, Elering started preparations in February, including design work, to speed up the repair of the cable. "The location specified last week was one of the main suspected fault locations from the outset. Repairing the cable in this location takes time, as a cable section of more than 500 meters long has to be replaced in one of the most technically difficult sections, i.e. at the borderline of the land and sea, where there is a sharp change in the height of the ground," Kebja said.

The cable is installed in the slope on the shore using the directional drilling method. "The geological conditions there are difficult and when planning the repair work, we have to find a solution to avoid its effects on the new cable section. In the sea, repair work is complicated since the ships normally used for laying the cable cannot get close to the shore, where the sea is shallow," said Kebja.

Moreover, the EstLink 2 cable is electrical-technically unique and the work required to repair it requires specific expertise and equipment. In addition to the cable, there are signs of mechanical damage in the transition joint of the submarine and land cable, located approximately 200 meters from the coastline. The final technical solution for both the cable being replaced and the transition joint will be specified during the design work that has started. "Fortunately, Elering has enough submarine power cable as well as sets for making cable transition joints in reserve," said Kebja.

Security of electricity supply is guaranteed in Estonia despite the fault of EstLink 2. In the security of supply assessments, Elering also takes into account scenarios where two elements important for the operation of the electricity system in the Baltic countries are out of order at the same time, for example, the case where in addition to EstLink 2, the Lithuanian-Swedish connection is not functioning. Even in this case, it is possible to keep the system running.

Historically, EstLink 1 and EstLink 2, operated by Elering, have been among the most reliable direct-current connections in Europe. However, failures do occur in direct-current connections. For example, in 2017, the repair of the Moyle submarine power cable between Scotland and Northern Ireland, similar to EstLink 2, lasted from February to September.