IFA (Interconnexion France-Angleterre)

Eight cables lie on the bed of the Strait of Dover between Folkestone and Sangatte, rated at 270 kV. RTE puts the route at 70 km of cable, 45 km of it under the sea. They are arranged as two fully independent bipoles of 1,000 MW, and that split has kept IFA partly running through damage that would have silenced a single-circuit link.

The present scheme is the second one on this crossing. An earlier 160 MW link built by ASEA opened in 1961 between Lydd and Echinghen, and it was shut down in 1984 because fishing gear kept damaging the cables. Work on its replacement started in 1985 and the new link entered service in 1986, with converter stations at Sellindge in Kent and at Les Mandarins in Bonningues-lès-Calais. The thyristor valves were renewed in 2011–2012.

The commercial logic has hardly changed in forty years. France had surplus generation and Britain was a willing buyer, so the power has mostly moved north: in 2006, according to the HVDC Cross-Channel article, 97.5% of the energy transferred went from France to Britain. Before 2021 the link was available around 98% of the time, among the best rates in the world for a scheme of its kind.

Two events broke that run. In November 2016, during Storm Angus, a ship dragging its anchor cut four of the eight cables and halved the capacity; repairs were finished by the end of February 2017. Then in September 2021 a major fire at the Sellindge converter station shut the link down. National Grid planned to bring half the capacity back by 20 October 2021 and to restore the full 2,000 MW by October 2023. For a link built as two halves, losing both at once was the scenario the design had been meant to avoid.

IFA now shares the crossing with two younger neighbours. IFA2 lands in Hampshire and Normandy, and ElecLink runs through the Channel Tunnel and connects into the same Sellindge and Les Mandarins substations. Both use voltage-source converters, while IFA remains a line-commutated scheme, the older of the two HVDC converter families. The List of HVDC projects still gives it the same ±270 kV and 2,000 MW rating it had when the cables were first energised in 1986.