World first for ESB

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Mat Cunningham, ESB Networks Area Manager, outlines the background to the cable fault, and the challenges involved in restoring electricity for the islanders.

“All three Aran Islands lost supply on a Friday and while power was restored to Inis Mór within hours, a huge effort was required to transport and activate generators and transformers on Inis Oírr over that weekend, restoring power to the two islands on the Monday. “Meanwhile, ESB Networks and ESB International crews began intensive underwater investigation, using electrical surges to pinpoint the exact fault position along the 10.5km cable in early October, located at 20 metres depth.

“A team of 11 highly specialised Irish divers completed 97 separate diving operations as part of the repair. ESB Networks are very pleased to report that, following the use of highly innovative repair methods by ESB International and extensive testing, both islands have now been successfully reenergised.”

ESB International Managing Director, Ollie Brogan, explains the cutting edge technique that was used to complete the repair.

“The traditional method of repairing a subsea cable would be to haul the cable onto a barge or ship and make the repair on the deck of the ship. However, in this case trained divers accessed the faulty part of the cable through a pressurised habitat, mounted around the cable. The habitat is a world first, used in 2014 for the first time to successfully repair the Moyle Interconnector in situ on the sea bed.

“The habitat was based on the design of a hospital incubator, giving access to the cable through holes in the side. Windows and mirrors are also fitted to give divers 360 degree views of the cable. Lights and cameras within the habitat means that supervision of divers’ repair work could take place from a surface control cabin.”

Watch a video of the repair at http://youtu.be/gtUS-nCS9cE