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Customer Success Story

Successful testing of the first of six single-phase 700 MVA, 420/27 kV Shell Generator Step-up Transformers

Enabling low carbon electricity generation to support the energy transition

Hitachi Energy reached a milestone by having successfully tested the first of six single-phase 700 MVA, 420/27kV Generator Step-up Transformers in Shell Form Technology at the Cordoba factory in Spain. One of the world's largest and most powerful single-phase generator step-up transformers.

With over 140 units delivered for nuclear applications, Hitachi Energy from the Cordoba Factory has a long-proven experience in the industry, being one of the leaders in terms of technology and quality.

The Generator Step-up is the main critical link between the generation and transmission network, being continuously in operation at almost full load, and being subject to dielectric, thermal, and mechanical stresses, including those associated with short circuit faults in the network.

Those very large transformers have a compact design, taking advantage of the shell technology to reduce the footprint and have an optimized design in terms of losses, with reduced operating and hot spots temperature to secure a long life expectancy.

Hitachi Energy power transformers stand out for their reliability, maximizing the safety of operations, optimizing the design control, and field execution, and extending the lifetime power plant, reducing the handover time, project delays, and cost overruns.

The transformers include Hitachi Energy's TXpand™ technology to make the transformers explosion-proof, increasing safety in case of internal failures.

Three transformers together weigh around 1.200 tons (400 tons each). They are unique in their class given the combination of power rating and voltage levels.

Hitachi Energy addressed different challenges in terms of quality and complexity, having as a result, a reliable tailor-made product that fulfilling the customer's high-level standards

The power plant will generate about 1.8 GW for low carbon electricity, cutting carbon emissions, and supporting the energy transition.

Main data
Product GSU Transformer
Power Rating 700 MVA 420/27 kV
Technology Shell form
1-ph 700 MVA, 420/27kV GSU Transformers

Generator Step-up (GSU) Transformers (GSU)

Hitachi Energy offers generator step-up transformers (GSU), which are the critical link between the power station and the transmission network, often operated day and night at full load. Learn more.
Hitachi Energy's power transformers

Power Transformers

Hitachi Energy offers a complete range of power transformers and related components and parts, including over twenty 800 kV UHVDC and over five hundred 735 - 765 kV AC units.
Hitachi Energy Power Transformers


Hitachi Energy offers distribution and power transformers, Dry-type and EconiQ™ Transformers as well as services, for industrial and commercial applications.

Nuclear Energy

Nuclear energy is part of today’s generation mix. We leverage deep industry expertise to meet the challenge of extending the lifetime and safe operation of new and existing plants.