Energy / SSEN Transmission responds to subsea cable concerns

SSEN Transmission has insisted that its Caithness-Moray HVDC subsea link currently has an availability rate of 99.8 per cent.

The company came under fire from the chairman of anti-Viking campaign group Sustainable Shetland earlier this week after the SSEN Transmission project director John Scott described the technology as very reliable in an article published by Shetland News last week.


Listing a series of failures in a number of different subsea cables at various locations, Frank Hay questioned the credibility of the company’s statement, describing SSE’s confidence as ”somewhat misplaced”.

A fact check of SSEN’s cable reliability claims


However, a SSEN spokeswoman said in response that the company could only comment on the subsea cables it operated.

The spokeswoman said the Caithness–Moray cable was still under construction when a fault was discovered and repaired in early 2018.

She added: “As the transmission owner in the north of Scotland, our first priority is to provide a safe and reliable supply of electricity to the communities we serve.


“High Voltage Direct Current (HVDC) technology, which will be used to connect Shetland to the GB mainland transmission system, provides the most efficient and reliable means of transmitting large amounts of power over long distances via subsea cable and plays an important role in facilitating the transition to net zero emissions.

“The Caithness-Moray HVDC link, which has been operational since January 2019, currently has a 99.8 per cent availability rate, having been unavailable only during pre-planned outages.

“The Shetland HVDC link, which is scheduled to be fully operational by 2024, has been designed to be protected against potential damages and will be buried in the sea bed via a remotely operated submersible units which cut the trench in which the cable is laid at a specified depth, which is then covered by protective materials.”