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Hitachi Energy has unveiled a groundbreaking advancement in transformer technology with the successful testing of the world's first 765kV single-phase natural ester transformer. This innovation represents a significant leap forward in high-voltage alternating current (HVAC) transmission, delivering a solution that is not only environmentally responsible but also exceptionally reliable and safe for utility-scale applications.
With its unprecedented voltage class, the 765kV natural ester transformer establishes a new industry benchmark, paving the way for more sustainable, resilient, and future-ready power grids.
Transformers operating at 765kV enable the bulk transmission of electricity across vast distances with minimal losses. Their role is pivotal in enhancing grid efficiency, fortifying system stability, and ensuring uninterrupted power delivery. As a strategic asset in grid expansion, a single 765kV transformer can support the electricity needs of a medium-sized city with a population of up to 250,000, highlighting its immense utility in modern infrastructure planning.
This development directly supports energy providers in addressing the ever-increasing global demand for power, while reducing the carbon and spatial footprints of transmission networks.
The development and successful validation of the 765kV ester-filled transformer further extend the application horizon of Hitachi Energy’s proprietary TrafoStar transformer technology platform. Used globally across all of Hitachi Energy’s transformer manufacturing sites, the TrafoStar platform ensures uniformity in design, engineering precision, and rigorous quality control.
The transformer recently passed stringent testing protocols at both the internationally recognized KEMA Laboratories and the Shenyang Transformer Research Institute in China—an emphatic endorsement of its performance and reliability under the most demanding conditions.
Traditionally, mineral oil has been the default insulating and cooling medium in power transformers due to its well-established electrical properties. However, the global energy sector's pivot towards greener technologies has accelerated the adoption of alternative insulating fluids such as natural esters.
Natural ester fluids boast superior fire safety characteristics, with flash and fire points that are approximately twice that of conventional mineral oils. Their self-extinguishing nature markedly enhances operational safety—particularly critical in dense urban or environmentally sensitive areas. Furthermore, natural ester oil biodegrades by 100% within 28 days, substantially minimizing ecological impact in the event of leaks or spills.
This transformer also integrates Hitachi Energy's TXpand™ technology, a rupture-resistant tank design that further elevates safety by mitigating the risk of explosions under extreme internal pressure scenarios.
As global electrification accelerates and energy systems undergo profound transformation, the deployment of innovative and sustainable transformer solutions becomes increasingly essential. Bruno Melles, Global Head of Transformers Business at Hitachi Energy, emphasizes the strategic relevance of this milestone: “With the dual forces of energy transition and surging electricity demand, the deployment of advanced transformer technologies has never been more crucial.”
Natural ester-filled transformers offer a potent combination of efficiency, environmental compatibility, and operational safety, making them ideally suited for deployment in ecologically sensitive areas. Melles underscores Hitachi Energy’s collaborative approach with clients and partners to upgrade ultra-high voltage infrastructure and develop renewable energy projects, building a cleaner, safer, and more resilient global energy landscape.
Transformers are integral to every stage of the electrical value chain—from generation to end-user consumption. Typically, electric energy traverses four to five transformers before reaching its destination. In this context, the 765kV HVAC system stands as a cornerstone of power grids across several continents, including North America, South America, South Africa, and key regions in Asia such as China.
By bolstering this segment with ester-insulated alternatives, Hitachi Energy is reinforcing the backbone of tomorrow’s power systems.
With over two decades of dedicated research and deployment in natural ester transformer technology, Hitachi Energy’s products now serve over 40 countries and regions worldwide. The company’s TrafoStar platform has yielded over 30,000 transformers to date, underpinned by an integrated quality management system that governs everything from raw materials to manufacturing processes and testing.
This structured, globally synchronized platform fosters continuous collaboration, knowledge sharing, and innovation, ensuring that every transformer reflects the company’s unwavering commitment to excellence.
The debut of the 765kV natural ester transformer is not merely a technological achievement—it is a declaration of intent. It signals a bold move towards sustainable electrification on a massive scale, where safety, environmental stewardship, and performance coalesce. Hitachi Energy continues to lead by example, shaping a smarter, safer, and greener electrical future for generations to come.
