The Western High Voltage Direct Current (HVDC) Link is a major electricity transmission project being jointly developed by National Grid Electricity Transmission and Scottish Power Transmission. This £1 billion project is going to help bringing renewable energy from Scotland to homes and businesses in Wales and England. Worthy of note is that it sets a record in terms of voltage due to its 600kV and has a currently unmatched transmission capacity for long-haul systems of 2,200 MW. 

The Western Link project includes direct current subsea and underground cables. It consists of approximately 422km of cable, of which 385km are underwater. The link connects England with the landfall of the Wirral Peninsula and Scotland with landfall at the Hunterston area.

Throughout the UK, electricity is transmitted by alternating current. This project therefore incorporates a converter station at each end of the link to change the electricity from direct current to alternating current to enable it to be used within the existing electricity transmission system.

In summer 2017, ASDG was appointed again by Prysmian to execute Post-Lay Burial operations by means of jetting of approximately 42.5 km at the deeper section of the route (from approx. KP 176 to KP 223). The SoW included the utilization of MPSV Astrea and our latest development, a jetting vehicle of 1.3 MW power namely the AssoJet III. Furthermore, ASDG scope of work was also including the installation of mattresses at crossings locations as well as at route sections with hard seabed conditions by utilizing MPSV Argo and ASDG mattresses installation frame AssoMat II.

Project was completed in August 2017


Vessel / Equipment used

  • Astrea
  • Argo
  • AssoJet III
  • AssoMat II
  • Vector M5


Project Specifications

Western HVDC Link - PLIB & Mattresses Installation

Prysmian PowerLink Srl
Cable Type:
Power 2 x 600kV HVDC & 1 FO
Cable Weight:
Power: 57.7Kg/m FO: 3Kg/m in air
Cable Diameter:
Power: 137mm FO: 35mm
Service Provided:
Cable Protection - Mattresses Installation
National Grid Electricity Transmission & Scottish Power Transmission
Jetting Length & Burial Depth:
42,460m @ 1.5m and 2.0m
Alternative Protection:
1,055m mattresses installation
Max Water Depth: