A cable fault has left the Moyle interconnector between Scotland and Northern Ireland operating at half of its normal 500MW capacity.
The southern high voltage cable has been disconnected after it tripped in the middle of the afternoon on Saturday (18 February).
An initial investigation by the operator Mutual Energy indicated that the fault is located offshore in waters around 140 metres deep. They said it is too early to say whether the cable has been damaged following “some kind of strike”, adding that further investigation is needed to pinpoint the precise location and cause of the fault.
In the meantime, Mutual Energy will begin to gather together the resources needed for the repair. The operator said depending on availability of resources and the nature of the seabed it should take around six months to complete.
“This is very much an unexpected event in that the fault relates to the high voltage element of the interconnector which is robust and well established technology,” the company said in a statement. “It is regularly tested, passing all tests, and has operated without any problems since installation over 15 years ago.”
The interconnector was only returned to full capacity around a year ago after Mutual Energy completed the replacement of the low-voltage cables. It had been operating at half capacity since July 2012 due to a “series of faults” beginning in 2010.