20MVA to 100MVA | Up to 145kV

At South Wales Transformers, our Medium Power Transformers are purpose-designed and manufactured to meet the demanding requirements of grid-connected substations, large industrial facilities, and utility-scale renewable energy generation projects. Every transformer is designed, manufactured, and tested in full compliance with IEC 60076-1, ensuring the highest standards of performance, safety, and reliability throughout the full operational service life of the asset.

Our medium power transformers are oil-immersed units, utilising high-quality cellulose insulation systems as standard, with Thermally Upgraded Paper (TUP) insulation available upon request for applications requiring enhanced thermal performance, in full accordance with IEC 60076-14. At this power rating, all units are supplied with a conservator tank as standard, providing the thermal expansion capacity required for reliable long-term operation across the full load range.

Cooling arrangements are carefully engineered to suit the specific rating and site conditions of each project. ONAN cooling is standard for the lower end of the rating range, with ONAF and OFAF forced cooling options available for higher rated units where site thermal conditions and load profiles demand a more active cooling solution.

Both On-Load Tap Changing (OLTC) and De-Energised Tap Changing (DETC) options are available across the full rating range, providing the flexibility required to meet the precise voltage regulation demands of transmission and distribution network operators, large industrial power consumers, and renewable energy park collector substations. All units are ground mounted and engineered for seamless integration into outdoor substation environments.

Every transformer undergoes a comprehensive programme of routine factory acceptance testing prior to despatch, carried out in full accordance with IEC 60076-1, with type testing and special testing available upon request to satisfy specific project, network operator, or grid code requirements.