Sellafield G9 & G10 Replacement

The scope of works involved for the replacement Grid Transformers at Sellafield included the design covers for the protection for the new 132kV/11.5kV Grid Transformers, encompassing both the new protection associated with the replacement GT9 & GT10 transformers, as well as interfacing the new protection to existing equipment that is to remain in service.

GT9 & GT10 protection, control, power supplies and related equipment were arranged into suites of panels dedicated to each transformer. Each suite of panels were located in rooms that were physically separate, such that no single common mode of failure will result in the loss of supply from both transformers.

Modifications were required to the existing 11.5kV Switchboard and also the 132kV GIS.

New equipment required included;

• GT Protection and Intertripping Panels
• AVC Relay Panels
• LVAC Boards
• 110V DC Battery Boards
• Fibre Optic Splice Boxes
• Local Alarm Panel Wall Boxes
• Local Marshalling Cabinets

Morson Projects were responsible for the production of all the schemes and general arrangements so that the protection panels could be built. Morson Projects had to interface with all manufacturers’ equipment wiring diagrams detailing addition of multicore details.

Site visits were required to as-built the existing LV & HV Protection Panels so that the new interface protection could be added.