765 kV Power: The efficient and high-capacity backbone to advance North America industrial electrification
Blog Post | 27.06.2025 | 7 min read | Douglas Wolken
The 21st century has triggered the era of electrification driven by the target to reduce carbon emissions, rapid urban growth, the rise of data centers, electrical mobility, and industrial plants transitioning away from fossil fuels.
The electricity grid is at the heart of this change, with the energy sector trying to balance three tough demands: keeping power affordable, ensuring it's always available (security), and making it clean and sustainable.
To meet growing demand and integrate cleaner energy sources, we need strong, efficient, and resilient transmission infrastructure – and high-voltage (HV) transmission is the optimal way to move large amounts of electricity efficiently over long distances.
HVDC (High-Voltage Direct Current) systems fit long-distance, point-to-point transmission from far-off sites or offshore, while HVAC (High-Voltage Alternating Current) systems support interconnected power grids, like those in North America and other regions. As electrification grows, the 765 kV ultra-high-voltage (UHV) AC transmission system becomes crucial for delivering reliable and efficient power.
Among the most important of these UHV technologies is the 765 kV AC transmission system. It's proving to be essential for reliably delivering large-scale power where industries need it most. This technology isn't just about moving power; it's a strategic piece of the puzzle for enabling energy-intensive industries to electrify at scale and build the reliable and efficient grid of the future.
Hitachi Energy has been a pioneer in HVDC and HVAC transmission, with an extensive installed base and vast experience, and continues to lead this transition, supporting our customers, partners, and the industry. We continue to drive transformation through our people’s knowledge, innovation, and systems expertise, helping industrial sectors achieve large-scale electrification and shape a scalable, reliable, and efficient grid of the future.
765 kV UHV: Building long distance reliability
To explain why 765 kV AC transmission is strategic for powering distant industries, we need to consider industrial electrification. This means factories and plants previously powered by fossil fuels on-site are now plugging into the electricity grid.
This requires not only cleaner ways to generate electricity but also efficient transmission of large amounts of power. The 765 kV ultrahigh-voltage AC transmission system is specifically designed for this task. It offers greater efficiency and reduced land use, making it especially effective for connecting remote generation to energy-intensive industries like oil and gas, manufacturing, chemicals, and data centers.
These industries need a stable, high-capacity power supply without interruptions. As industry electrification scales up across North America, this level of transmission capability becomes essential to ensure grid resilience, reduce bottlenecks, and unlock new opportunities for industrial innovation and decarbonization.
765 kV transmission lines operate at one of the highest AC voltage levels used globally. These systems are built for:
Transmitting high volumes of electricity across long distances
Reducing transmission losses and optimizing efficiency
Supporting grid stability and inter-regional connectivity
The Permian Basin: A growing demand hub
To see the strategic importance of 765 kV technology in action, we can look at the Permian Basin, a major energy-producing region spanning West Texas and Southeastern New Mexico, known globally for its vast oil and natural gas production.
It produces millions of barrels of oil daily, contributing significantly to the US energy supply (in 2023 alone, it produced over 4.1 million barrels of crude oil per day).
It's also a major source of natural gas used by various industries, supporting petrochemical, manufacturing, and export markets.
As energy producers seek to decarbonize operations and improve efficiency, electrification of field equipment, processing facilities, and transport systems is becoming a strategic priority - not only for reducing emissions, but also for improving energy efficiency, system resilience, and long-term cost competitiveness.
Electrifying these energy-intensive operations places huge new demands on the local power grid. To handle this growing demand and to support the continued expansion of the region, the Southwest Power Pool (SPP) has proposed over 300 miles of new extra-high-voltage lines, including a 765 kV transmission corridor, to relieve grid congestion and power the next phase of Permian growth.
This proposal clearly signals that building 765 kV lines is a necessary strategic investment to effectively and successfully handle the scale of industrial growth and electrification.
The advanced technology behind 765 kV transformers
Demand for ultrahigh-voltage (UHV) transmission is increasing, so is the need for power transformers built to deliver extreme performance. Typically installed at key grid nodes, these transformers are essential for system efficiency, stability, and resilience.
Autotransformers are the preferred choice for connecting high-voltage levels—such as 765 kV to 345 kV, offering a compact, cost-effective alternative to traditional two-winding transformers. Their efficient design lowers initial investment and total cost of ownership while easing installation and transport.
With robust voltage regulation, autotransformers ensure stable, long-distance power delivery. Their advantages—cost savings, space efficiency, and operational performance—make them ideal for high-voltage applications.
Supporting this critical infrastructure requires deep expertise across electrical and mechanical engineering, materials science, and manufacturing. These transformers must endure extreme electrical stress, heat, and harsh environments—demanding advanced insulation and cooling technologies to ensure safe, reliable, and sustainable operation.
Main challenges of 765 kV Transformers
Extreme Insulation and Dielectric Requirements
At 765 kV, the electrical stress on insulation systems is significantly higher than at lower voltage levels. Transformers must be designed with enhanced insulation coordination, high dielectric strength, and advanced materials to withstand lightning impulses and switching surges. Managing internal clearances and field distribution is critical to avoid partial discharges and long-term degradation.
Thermal Management and Cooling
Due to the high-power ratings and operational demands, 765 kV transformers generate substantial heat. Efficient thermal design, including optimized oil circulation and cooling systems (ONAF, ODAF, etc.), is essential to maintain safe operating temperatures and extend asset lifespan — especially in hot or remote environments where grid loads are sustained.
Mechanical and Transportation Constraints
765 kV transformers are extremely large and heavy, often requiring single-phase design to facilitate transportation. This introduces logistical complexity — from factory handling and road clearance to installation at remote substations. Special lifting, routing, and assembly procedures are often required, making supply chain flexibility and local assembly capabilities crucial.
Component Integration and System Reliability
At this voltage class, every sub-component must meet exacting standards. Bushings, tap-changers, monitoring systems, and insulation fluids must perform flawlessly under UHV conditions. For example, bushing design and placement are critical challenges due to the high electric field stress. Any failure in auxiliary components can lead to catastrophic system outages, so vertical integration and in-house component manufacturing are key to ensuring long-term reliability.
The 765 kV journey
Contributing to the journey with experience and innovation
Deep technical foundation in UHV systems
With the first units developed in the 1960s, and now more than 500 units delivered globally, Hitachi Energy 765 kV transformer solutions are rooted in decades of internal R&D and reflect decades of focused research, field learning, and applied engineering. This history has allowed us to contribute meaningfully to the evolution of ultrahigh-voltage systems, supporting project teams from early specification through to deployment.
A globally connected, locally responsive network
Our distributed manufacturing capabilities are designed to respond to real-world challenges, enabling project continuity even in dynamic or remote environments. Guided by our global design platform TrafoStar, we maintain a consistent standard of quality while adapting to regional needs.
Thanks to our multi-location manufacturing strategy, we offer customers superior delivery agility, even in constrained markets. This flexibility is vital when building in remote or logistically challenging environments like the Texas basin.
Innovation anchored in sustainability goals
The introduction of 765 kV transformers marks a step forward in combining high performance with environmental responsibility. Originally developed in China and now deployed globally, this new solution empowers users with the possibility of opting for transformers filled with natural ester instead of common mineral oils, leveraging the benefits of a biodegradable, fire-resistant insulating fluid, with a flash point twice as high and self-extinguishing properties.
A legacy of manufacturing precision
Our long-established facility in Varennes, Canada, has produced more than 100 high-voltage units in the 735–765 kV range. This legacy reinforces a culture of precision, continuous improvement, and deep domain expertise in large-scale transformer manufacturing.
Short circuit proven designs
Hitachi Energy transformers are designed to ensure maximum reliability and availability. The tests verify the mechanical and electrical stability to withstand high forces. Hitachi Energy conducted the short-circuit test at KEMA, an independent laboratory in the Netherlands, according to International Electrotechnical Commission (IEC) standards. Until now, Hitachi Energy has short circuit tested over 170 power transformers of various ratings and demonstrated best in class short circuit performance, with a failure rate that is less than half of the market average.
System integration through vertical expertise
We maintain full control over critical components, allowing us to design for reliability at the system level — not just the unit level. This vertical integration supports better alignment between performance expectations and real-world operating conditions.
Looking ahead: Building the backbone of electrified industry “one phase” at a time
The trend of industries moving toward electrification is gathering speed across North America. Electrifying operations in places like Texas leads to lower emissions, more efficient processes, and better control.
Using single-phase UHV transformer solutions is a practical approach for these demanding applications because they are easier to transport and install, especially in challenging locations. However, successfully implementing these large-scale projects, dealing with things like getting equipment to the site or placing components correctly, requires partnering with experts who truly understand this complex technology.
Hitachi Energy is optimally positioned to advance this transformation and provide the essential solutions needed to build the strong, reliable grid required for North America's electrified industrial future, one phase at a time.
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