Rhyd Y Foel, North Wales Client: ScottishPower Project: Replacement of 33/11kV 7.5MVA ONAN transformer Duration: 12 weeks Main Contractor: D & A Systems Ltd D & A Systems were commissioned by ScottishPower to replace the existing 33/11kV 7.5MVA ONAN Transformer at Rhyd Y Foel Primary Substation as part of their asset replacement programme. In essence, the job entailed construction of a new fully bunded transformer compound complete with sump pump to accommodate the new transformer.  As part of the scheme it was necessary to reconstruct the 33KV Cable Termination complete with surge arrestors and to replace the overhead busbars between the 33kV Circuit Breaker and Sealing End Insulators. As appointed CDM Principal Contractor, D & A Systems were responsible for supervising the crane lift by ABB to position the 25tonne transformer into its final location. Due to the rural location of the site and the narrow lanes it was necessary to install suitable trackway for the 80tonne crane to access the site and undertake the lift safely. D & A Systems were responsible for witnessing the pre-commissioning tests by the transformer manufacturer (ABB) and full commissioning of the transformer voltage control and protection scheme.