Gwynt y Môr OFTO
OperationalOffshore GridGB576 MW132 kV126.8 km2013
Basic information
9 fieldsAlso Known As
Gwynt y Môr OFTO plc · GYM OFTO · Gwynt y Môr offshore transmission link · Gwynt y Môr OFTO TR2
Status
operational
Capacity
576 MW
Project Company
Type
offshore grid
Transmission Model
Developer Build & Transfer
Expected Life
20 years
Website
Supply Chain (12)
Project Timeline (44)
~Jul 2025Cable RepairStale
In April 2025, N-Sea Group was again contracted by Gwynt y Môr OFTO plc to perform a further repair on one of the four 132 kV export cables that form part of the Gwynt y Môr transmission assets, involving replacement of a 5 km section from the onshore transition joint bay toward the offshore platform. The summer 2025 campaign, to be executed using N-Sea’s dedicated cable repair vessel CURO and supported by in-house survey, UXO and data teams, will include HDD pull-in under a railway, shore-approach dredging, jointing, testing and burial of the new cable and is described as the third offshore repair N-Sea has undertaken for this client.
24 Apr 2025Cable Repair
On 24 April 2025, N‑Sea Group announced it had been awarded a further contract by Gwynt y Môr OFTO plc to repair one of the four 132 kV export cables, including replacing a 5 km section from the onshore transition joint bay towards the offshore platform, with scope covering HDD pull‑in under a railway, shore approach dredging, jointing, testing, and burial using the cable repair vessel CURO.
9 Dec 2024Major Maintenance
From 9 to 17 December 2024, Gwynt y Môr OFTO took transformer SGT1 out of service to replace its bushings, resulting in an eight‑day outage for this major asset, for which the company plans to submit an Exceptional Event claim.
22 Oct 2024Revenue Application
On 22 October 2024, Gwynt y Môr OFTO plc submitted an Income Adjusting Event (IAE) Notice to Ofgem in relation to subsea export cable 3 (SSEC3), seeking recovery of further uninsurable costs arising from a latent defect in the PE sheath of the fibre optic cable and the complex Stage 3 repair, including PBCE interest costs totalling approximately £0.36 million, and requesting a revenue adjustment from the 2025/26 regulatory year.
30 Aug 2024Cable Repair
Gwynt y Môr OFTO completed the Stage 3 Repair of subsea export cable 3 (SSEC3) on 30 August 2024 under a contract signed on 16 May 2024 with a repair contractor (identified in project documentation as N-Sea), using two jack-up barges HavenSeaRiser 4 and HavenSeaSeven and associated vessels to replace and joint new 132 kV export cable between the transition joint bay and offshore, in a complex nearshore environment involving HDD ducts, beach quadrants and constrained joint bay space.
29 Aug 2024System Testing
Following the Stage 3 repair on subsea export cable 3 (SSEC3), Gwynt y Môr OFTO plc carried out system testing before returning the circuit to service. On 29 August 2024 senior authorised persons transferred control to the offshore substation, signed the GYM Equipment Acceptance Certificate and initiated a soak test of the repaired cable section, which ran for about 21.5 hours until 21:00 on 30 August 2024, after which the circuit was made available and re‑energised with a 90 MW export cap. Cable testing and associated jointing at the transition joint bay were completed as part of this testing phase.
16 May 2024Procurement Other
Gwynt y Môr OFTO plc signed a repair contract with a specialist repair contractor for the Stage 3 Repair of subsea export cable 3 (SSEC3) on 16 May 2024, appointing the contractor to execute a complex offshore and onshore cable replacement and jointing campaign between the transition joint bay and KP5.1.
Dec 2023Cable Repair
In December 2023, subsea export cable 3 (SSEC3) on the Gwynt y Môr OFTO system suffered a main power core fault, referred to in the licensee’s Income Adjusting Event notice as the 2023 Cable Failure, prompting development of an agreed multi-stage repair plan including local repair near the transition joint bay and replacement of cable between the TJB and approximately KP5.1.
May 2022Cable Repair
N-Sea Group carried out a preemptive repair on one of the four 132 kV export cables serving the Gwynt y Mor offshore wind farm from May 2022, having been awarded the contract in March 2022. This was the first of what became multiple N-Sea repair campaigns on the Gwynt y Mor export cables, with subsequent repairs in 2024 and planned for 2025.
15 Apr 2022Inspection Survey
Around 15 April 2022, the survey vessel Titan Endeavour performed a pre-construction survey of the Gwynt y Mor export cable corridor over up to seven days, collecting route data ahead of maintenance work on one of the export cables. This survey preceded the N-Sea preemptive repair campaign that commenced in May 2022. Note: date is from pre-event Notice to Mariners; survey confirmed indirectly by subsequent N-Sea repair completion (Sep 2022).