AI data centers are changing the electrical infrastructure behind computing almost as quickly as they are changing the servers themselves. As GPU clusters become denser and rack power continues to rise, moving enough electricity through the facility without excessive current, conductor size, conversion losses, and electrical footprint has become a much larger design challenge.
This is why 800V DC power distribution is moving from an emerging concept toward a more defined architecture for next-generation AI data centers. In 2026, NVIDIA, Google, Microsoft, and the Open Compute Project have continued pushing the industry toward common 800VDC system requirements, while equipment manufacturers are developing the power conversion, protection, distribution, and rack infrastructure needed to support the transition.
But the arrival of 800V DC creates an obvious question for the conventional power transformer:
If more of the data center distributes power in DC, what happens to the transformers that have traditionally connected the facility to the grid and supplied its internal AC network?
The answer is not that power transformers suddenly disappear.
800V DC mainly changes how power is delivered through the downstream part of the data center. Large facilities still need to receive electricity from an AC utility network, transform incoming voltage, operate substations, distribute power across a campus, provide isolation, coordinate protection, and support cooling, auxiliary systems, energy storage, and future expansion.
For HONLE, this means the transformer application is evolving together with the data center architecture. 35kV and 110kV oil-immersed power transformers, distribution transformers, and SC(B) dry-type transformers can continue to serve different parts of the upstream and facility-level AC system, even when the final delivery path toward high-density AI racks increasingly uses 800V DC. HONLE’s current transformer range includes oil-immersed, dry-type, 35kV, and 110kV solutions for different distribution and substation requirements.
Why Are AI Data Centers Moving Toward 800V DC?
The interest in higher-voltage DC is closely connected to one basic electrical relationship: when more power has to be delivered at a relatively low voltage, current rises quickly.
That becomes increasingly difficult as AI computing density increases.
Higher Voltage Reduces Current
A high-density AI hall can require enormous amounts of power within a limited physical area. At lower distribution voltages, carrying this power requires higher current, which can mean larger cables and busbars, more copper, greater resistive losses, more heat, and more space occupied by electrical equipment.
Raising the distribution voltage allows the same power to be transferred at lower current.
This does not remove every electrical challenge, but it helps address one of the most important physical constraints created by high-density computing: how to move more power through a limited amount of space.
NVIDIA now describes 800VDC as part of its power architecture for future AI factories, with the transition expected to progress from existing AC infrastructure through hybrid systems and eventually toward more extensively DC-based facilities.
Fewer Conversion Stages Can Simplify the Power Path
Computing equipment ultimately relies heavily on DC power, while the utility grid supplies AC power.
In a conventional data center, electricity may pass through several stages before reaching the computing hardware:
Utility AC → Power Transformer → AC Distribution → UPS / Rectifier → Lower-Voltage DC Conversion → IT Equipment
The exact arrangement varies from project to project, but each conversion stage requires equipment, cooling, control, protection, and physical space.
An 800VDC architecture can move the major AC-to-DC conversion farther upstream and distribute higher-voltage DC closer to the computing racks:
Utility AC → Transformer / AC-to-DC Power Conversion → 800V DC Distribution → Rack-Level Conversion → AI Equipment
The main change therefore occurs after power has already entered the facility.
The external utility network does not become an 800VDC grid simply because the computing racks are supplied by DC.
Where Does the Power Transformer Fit in an 800V DC Data Center?
It helps to look at an AI data center as a complete grid-to-rack power chain rather than focusing only on the voltage used at the rack.
A large campus may include:
Utility Grid → Main Substation → Power Transformers → Medium-Voltage Distribution → AC-to-DC Power Blocks → 800V DC Distribution → Compute Racks
The exact arrangement can be different, but this simplified chain shows why a change near the rack does not automatically remove the transformer upstream.
Incoming Utility Voltage Still Has to Be Transformed
Large data centers may connect to medium-voltage, sub-transmission, or higher-voltage networks depending on site capacity and local utility conditions.
An 800V DC bus cannot directly replace the equipment required to connect such a facility to the grid.
For example, where a campus receives a higher-voltage utility supply, an oil-immersed power transformer may first reduce the incoming voltage to a suitable medium-voltage level for site distribution.
The downstream conversion system can then create the required 800VDC bus.
A possible architecture is therefore:
Utility Grid → High-Voltage Power Transformer → MV Distribution → AC-to-DC Conversion → 800V DC
In this arrangement, the power transformer and the DC architecture are not competing technologies. They perform different functions at different positions in the system.
Substations Remain Central to Large AI Campuses
AI infrastructure is increasingly being developed at campus scale.
A project may include several data halls, multiple utility feeds, cooling plants, battery systems, backup generation, switchgear, dedicated substations, and future expansion zones.
Power has to be received, transformed, protected, divided into feeders, and delivered to different power blocks throughout the campus.
The final rack distribution voltage does not remove these requirements.
In fact, as individual data halls become more power-intensive, the capacity and configuration of the upstream substation can become even more important.
Where Can HONLE Power Transformers Fit in This Architecture?
Not every transformer inside an AI data center serves the same purpose. The required transformer type depends on where it is installed in the power chain, the incoming voltage, capacity, environment, redundancy philosophy, and downstream equipment.
HONLE manufactures both oil-immersed and dry-type transformers, including transformer solutions for 35kV and 110kV systems.
That allows different transformer technologies to be considered for different parts of a data center power system.
110kV Power Transformers for Higher-Voltage Grid Connections
A very large AI campus may require a dedicated substation or connection to a higher-voltage utility network.
Where the project electrical design uses a 110kV voltage level, a 110kV oil-immersed power transformer can form part of the grid-side transformation system, reducing incoming voltage before power is distributed through the campus at the required downstream AC level.
Whether 110kV is appropriate depends entirely on the local utility network and project design. An 800VDC rack architecture does not determine the grid connection voltage.
The important point is that the higher-voltage transformation stage remains upstream of the DC distribution system.
35kV Power Transformers for Medium-Voltage Infrastructure
A 35kV network may be used in medium-voltage distribution or substation arrangements where it matches the local system and facility design.
HONLE’s 35kV oil-immersed power transformer range can therefore be considered for relevant medium-voltage substation and distribution applications rather than for direct connection to the 800VDC rack bus.
The system relationship may look more like:
35kV AC Network → Power Transformer / MV Distribution → Power Conversion Equipment → 800V DC
This distinction matters because it keeps transformer selection tied to the real electrical architecture instead of treating “800V DC transformer” as a single product category.
Oil-Immersed Transformers for Outdoor and Substation Applications
Oil-immersed transformers remain well suited to many outdoor substations and higher-capacity power distribution applications because of their established cooling structure and long experience in utility and industrial networks.
For a data center campus, they may be installed in outdoor substations or other parts of the main distribution infrastructure depending on voltage, capacity, fire protection design, environmental conditions, and overall site arrangement.
HONLE supplies several oil-immersed transformer series in addition to its 35kV and 110kV power transformer ranges.
Dry-Type Transformers Still Have a Role Inside the Facility
Not every AC load in an 800VDC data center disappears.
Cooling equipment, pumps, fans, building services, control infrastructure, maintenance systems, and many auxiliary loads can continue to require conventional AC distribution.
Dry-type transformers are therefore still relevant for indoor electrical rooms and other controlled areas where voltage transformation is required.
HONLE’s SC(B) series dry-type transformers use cast-resin insulation and are designed for indoor distribution applications where installation environment, ventilation, thermal performance, and fire-safety planning are important.
The result is likely to be a mixed electrical environment rather than a simple “AC versus DC” choice.
Will Solid-State Transformers Eventually Replace Conventional Transformers?
Solid-state transformer technology is important to the 800VDC discussion because it creates another possible route between medium-voltage AC and high-voltage DC.
A conventional architecture may use separate transformer and rectification stages:
MV AC → Conventional Transformer → Lower-Voltage AC → Rectifier → 800V DC
An emerging solid-state transformer architecture could integrate more of these functions:
MV AC → Solid-State Transformer → 800V DC
In 2026, the Open Compute Project announced an MV AC-to-800VDC power conversion workstream and published the Solid-State Transformer Specification v0.3, developed through collaboration involving Microsoft, Google, NVIDIA, and other industry participants.
This makes direct medium-voltage-to-800VDC conversion much more relevant than it was only a few years ago.
However, it should not be interpreted as proof that every future data center will remove conventional transformers.
Several architectures can develop at the same time.
An existing facility may retain its AC infrastructure and introduce 800VDC closer to the compute racks. Current industry roadmaps also include hybrid transition architectures that allow 800VDC power systems to integrate with existing AC infrastructure.
A new facility may place AC-to-DC conversion farther upstream.
Another large campus may continue using conventional grid-side power transformers while introducing solid-state conversion at selected medium-voltage power blocks.
The more useful question is therefore not whether one transformer technology “wins.”
It is:
At which point in the grid-to-rack power chain should voltage transformation, isolation, AC-to-DC conversion, and power control take place?
That answer can vary between projects.
How Does 800V DC Change Transformer Operating Conditions?
Even when the transformer remains on the AC side of the system, the downstream load profile still matters.
AI data centers are unusual electrical environments because their loads can be large, continuous, power-electronic, and capable of expanding quickly.
Continuous High Load Requires Strong Thermal Planning
AI training and inference infrastructure can maintain substantial demand for long operating periods.
Transformer capacity should therefore be considered together with real continuous load, temperature rise, cooling method, redundancy, expected utilization, ambient temperature, and planned future capacity.
A nameplate kVA or MVA value alone does not describe the complete duty.
The transformer has to operate within its thermal limits under the actual conditions of the project.
Power Electronics Keep Harmonics Relevant
Rectifiers, UPS systems, converters, server power supplies, variable-frequency drives, battery systems, and other electronic loads affect the electrical environment seen by the AC network.
Moving more of the facility toward 800VDC does not automatically eliminate harmonics.
Instead, it changes where the major conversion equipment is located and which part of the AC network sees the resulting current waveform.
Transformer design and system studies therefore still need to reflect the real characteristics of the connected power electronics.
Redundancy Changes the Capacity Arrangement
A data center rarely selects transformer capacity based only on the normal load.
The electrical design may have to maintain operation after one transformer, feeder, converter block, or other component is removed from service.
Depending on the redundancy strategy, the project may use several transformer units rather than one very large unit.
This affects transformer rating, impedance, switching arrangement, spare capacity, maintenance access, and the configuration of the surrounding switchgear.
Battery Systems Can Change the Upstream Load Profile
Battery energy storage fits naturally into a DC-oriented data center architecture because batteries are inherently DC devices.
Depending on how the battery system is integrated, charging, discharge, ride-through, and peak-management strategies can change the power profile seen upstream.
This makes coordination between transformers, power conversion systems, BESS, protection, and facility controls increasingly important.
The transformer may no longer serve a simple one-direction load. It may sit upstream of a much more actively controlled power system.
800V DC Can Make AI Data Center Expansion More Modular
One of the most important characteristics of modern AI infrastructure is the speed at which additional computing capacity can be added.
Large campuses are often easier to develop when electrical and cooling systems are organized into repeatable blocks.
A simplified structure may be:
Grid Connection
↓
Main Substation
↓
Power Transformers
↓
Medium-Voltage Campus Distribution
↓
Multiple AI Power Blocks
↓
800V DC Distribution
↓
Compute Racks
Instead of asking only how large one transformer should be, the project can consider how transformer capacity should grow together with the campus.
For example, the first construction phase may use several transformers supporting a defined number of power blocks. Additional transformers, feeders, conversion systems, and data halls can then be added as later phases are commissioned.
This can influence:
- transformer unit rating;
- number of transformers;
- redundancy philosophy;
- feeder arrangement;
- substation space;
- spare capacity;
- protection coordination;
- maintenance planning; and
- future interconnection points.
An oversized transformer installed for a distant future load is not automatically the best answer.
In some projects, several planned transformer stages can provide a better match between electrical investment and actual data center expansion.
For us as a transformer manufacturer, this means the project discussion should include both the first-stage duty and the intended final campus architecture.
What Does This Mean for AI Data Centers in the Middle East?
The Middle East is a useful example of why the upstream transformer system remains important even as downstream DC distribution changes.
New AI and digital infrastructure projects in markets such as Saudi Arabia and the UAE can involve large greenfield campuses rather than only modifications to older server facilities.
In this type of project, 800VDC is only one part of a much larger electrical planning problem.
Large Campuses Need Grid Capacity Before They Need 800V DC
Before a high-density AI hall can distribute 800VDC to its racks, the site must first obtain enough power from the local network.
Depending on the project scale, this can involve a new utility connection, substation construction, transformer capacity, medium-voltage distribution, switchgear, backup generation, and energy storage.
A well-designed DC bus cannot compensate for inadequate upstream grid capacity.
This is why the transformer remains closely connected to the overall development of large AI infrastructure.
High Ambient Temperature Has to Be Included in Transformer Design
Hot-climate projects also bring another practical issue: ambient temperature.
For outdoor oil-immersed transformers, actual site temperature affects cooling margin and thermal performance. Radiator arrangement, cooling method, loading, insulation system, temperature rise requirements, and installation conditions need to be considered together.
For indoor dry-type transformers, room temperature and ventilation remain equally important. A dry-type transformer cannot be treated as thermally independent simply because it is installed indoors.
The downstream system may be 800VDC, but the upstream transformer still operates according to familiar thermal principles.
Phased Growth Should Be Considered Early
New digital infrastructure clusters can also expand quickly.
A campus designed around an initial group of AI halls may later add more compute capacity, more cooling equipment, additional BESS capacity, or another utility connection.
Transformer and substation planning should therefore leave a practical path for expansion.
For HONLE projects, this can mean reviewing transformer capacity together with incoming voltage, final campus scale, number of planned construction phases, redundancy, ambient conditions, cooling requirements, and the surrounding electrical system rather than selecting a transformer from the first-stage load alone.
HONLE Power Transformers for the Changing AI Data Center Power Architecture
800V DC is a significant development in AI data center power design because it addresses a genuine problem: delivering much larger amounts of power to increasingly dense computing infrastructure without allowing current, copper, conversion equipment, and electrical footprint to grow at the same rate.
It will change the architecture between the facility power system and the AI rack.
What it does not do is remove every AC system upstream.
For many projects, the transition will be gradual:
Utility Grid → Conventional Power Transformer → MV Distribution → Power Conversion → 800V DC → AI Compute
Other projects may integrate solid-state transformers or move the AC-to-DC conversion stage farther upstream.
Existing facilities may adopt hybrid architectures while retaining much of their present AC infrastructure.
The electrical architecture can therefore change considerably from one project to another.
At HONLE, we manufacture oil-immersed and dry-type transformers, including 35kV and 110kV power transformer solutions, for different utility, industrial, infrastructure, renewable-energy, and power distribution requirements. Our transformer range allows the grid-side and facility-level AC requirements of a data center project to be considered separately from the downstream 800VDC architecture.
For an AI data center project, transformer configuration can be developed around the actual incoming voltage, required capacity, load profile, impedance, cooling conditions, ambient temperature, harmonics, redundancy strategy, installation environment, protection requirements, future expansion, and substation layout.
The power path from the grid to a GPU rack is changing.
But the basic requirement remains the same:
large amounts of electrical energy still have to be received, transformed, isolated, protected, controlled, and delivered reliably before they can support high-density computing.
800V DC changes where some of these functions take place.
It does not make the upstream power infrastructure disappear.
FAQ
Why are AI data centers moving toward 800V DC?
Higher-voltage DC allows large amounts of power to be distributed at lower current than lower-voltage systems. This can reduce conductor requirements, copper use, resistive losses, heat, and electrical footprint while supporting increasingly dense AI computing infrastructure.
Does an 800V DC data center still need a power transformer?
In many architectures, yes. Data centers normally receive AC power from the utility grid, while the 800VDC bus is created farther downstream. Transformers may still be required for grid connection, substation voltage transformation, medium-voltage distribution, electrical isolation, and auxiliary AC systems.
Can a conventional power transformer work with an 800V DC architecture?
Yes. A conventional transformer can supply an AC network that feeds rectifiers or other AC-to-DC power conversion equipment. The transformer and the 800VDC system perform different functions within the same power chain.
Does a power transformer convert AC directly to 800V DC?
A conventional power transformer changes AC voltage but does not by itself convert AC into DC. A separate rectifier or power conversion stage is normally required. Emerging solid-state transformer architectures can integrate voltage transformation, isolation, and AC-to-DC conversion more closely.
Can a solid-state transformer convert medium-voltage AC directly to 800V DC?
This is an emerging architecture. Medium-voltage solid-state transformer systems are being developed to combine voltage transformation, galvanic isolation, and AC-to-DC conversion, including MV AC-to-800VDC applications. The Open Compute Project is actively developing requirements for this type of system.
Will solid-state transformers replace conventional power transformers in AI data centers?
Not necessarily. Conventional transformers, solid-state transformers, rectifiers, and hybrid AC/DC systems can coexist in different parts of the same data center ecosystem. The appropriate architecture depends on grid voltage, facility size, existing infrastructure, reliability strategy, equipment availability, efficiency targets, and project economics.
Where can a 35kV power transformer be used in an AI data center?
Where the facility electrical design includes a 35kV network, a 35kV transformer can be used in the relevant medium-voltage substation or distribution stage. Its role is normally upstream of the 800VDC bus rather than directly supplying DC racks.
Can a 110kV power transformer be used for a large AI data center?
It can be considered where the campus connects to a 110kV network and the project electrical design requires that voltage level. The actual transformer rating and configuration must follow the utility connection, required capacity, redundancy arrangement, and substation design.
Are dry-type transformers still useful if the data center adopts 800V DC?
Yes. An AI data center can still contain many AC loads and indoor distribution systems. Dry-type transformers may be used for suitable indoor electrical rooms, auxiliary distribution, cooling-related loads, building systems, and other AC applications depending on the project architecture.
Does 800V DC make conventional power transformers obsolete?
No. Its strongest impact is on the downstream delivery of power to high-density computing equipment. Conventional power transformers can continue to support utility connections, substations, campus distribution, and other AC infrastructure even as the power system closer to the computing racks becomes increasingly DC-based.