CASE STUDIES

LVAC

National Grid Walpole 400/132KV Substation

Walpole

WARDPOWER were contracted to provide a complete LV Scheme including a Type Registered 912KVA Plant Room Generating Set and LVAC Board, a 1MVA Transformer and all associated works, however, we had to get rid of a few redundant items first. Out went:

  • 5 off Generating Sets
  • 6 off LVAC Boards
  • 2 off Mains Supply Boards
  • 2 off Auxiliary Transformers
  • All associated day tanks, exhaust systems, power and control cables, starter batteries and pipe work
  • Asbestos removal

Of course, the site needed to be completely operational during works so provision was made of a temporary generating set, along with a fuel tank and temporary distribution board and all associated ancillary equipment including installation and full commissioning.

Once this was done, civil works could commence.  The main supply building and block walls in the LVAC room were demolished, 220m of trenches were excavated for ducts and draw pits to be installed, brick supports from an existing tank bund were removed and 11T rated heavy duty precast trenches were installed across an access road from LVAC room to existing trenches.
Then the new stuff went in:

  • 912KVA Type Registered Generating Set including an integral bunded day dank with transfer system and bulk tank for 52 hours running at full load; Type Tested control panel suite; Plant room acoustics and an FM200 Fire Suppression System
  • Type Registered LVAC Board complying to NG TS 3.12.3 Issue 7
  • 1MVA, 11kV/433V Transformer
  • 2 off wall mounted link boxes for jointing of the existing feeder cables
  • A temporary Generating Set connection point on the external wall of the generator room
  • Electrical installation, along with high level cable containment including:
    • Load cables from transformer, Generator and temporary Generator connection point to the LVAC Board, and from the 11kV RMU to the new transformer.
    • An assortment of small power and control cables for all equipment
    • HV terminations
    • Earth connection for all new equipment to the site earth nest
  • Full Generating Set commissioning including primary injection testing and an 8 hour load bank test
  • Transformer commissioning in accordance with the manufacturers instructions
  • Commissioning of the LVAC Board including primary injection testing of all breakers