High-Voltage Data Center Architectures: Advantages and Challenges of Adopting 480VAC Three-Phase

Power Demands and the Future of Data Centers

Generative AI, the Internet of Things (IoT), and cloud computing are fueling an ever-growing demand for power. As a result, global demand for data center capacity is expected to increase at an annual rate of 19 to 22 percent until 2030.

Power requirements are spurring the development of new high-voltage data center architectures designed to maximize power density. While traditional data centers often rely on 250VAC single-phase power, today’s high-voltage alternatives include 277VAC single-phase power, 480VAC three-phase power, and even +/-400VDC.

The reason for the shift is simple. As large data centers expand, the power output required from their servers will soon exceed what can be practically delivered by standard 250VAC single-phase architecture — if it hasn’t already.

One potential solution involves bringing three-phase power deeper into the power distribution train. Typically, a data center’s power distribution unit (PDU) transforms the three-phase power received from the electrical grid into single-phase power. However, proponents of the three-phase approach could instead elect to run the three-phase power all the way to the power supply units (PSUs) within each rack. This article will explore the advantages and challenges of 480VAC three-phase power, including its impact on power capacity, efficiency, and equipment design considerations.

What Are the Limitations of 250VAC Single-Phase Power Architectures?

Traditional data center architectures often utilize 250VAC single-phase power. While this setup is sufficient for smaller data centers with racks requiring relatively low power inputs (up to ~8kW), scalability becomes a major challenge as power demands increase. Today’s high-performance data center designs demand significantly more power per rack. A decade ago, 30kW per rack was considered standard. Now, racks that require over 100kW in power density are becoming increasingly common.

Standard 250VAC single-phase simply cannot supply the required power for such data centers without significant disadvantages. Ohm’s Law dictates that in order to achieve power increases at constant voltage, an increase in current is required. To mitigate the increased heat associated with higher currents, the conventional solution is to increase the cross-sectional area of the conductor — essentially a thicker cable.

Larger cables introduce new problems, however. They are more expensive, cumbersome to route and manage, and occupy valuable space within data center infrastructure. A more effective strategy is to keep the amperage low and increase the voltage to meet power demands instead.

In response to this reality, data centers across the world are exploring high-voltage architectures that optimize power distribution. One such solution involves running 480VAC three-phase power deeper into the power train, allowing data centers to leverage up to three times the power capacity while also gaining efficiency and operational benefits.

What Are the Advantages of 480VAC Three-Phase Power Architectures?

Before exploring the benefits, it is necessary to understand how power flows through a data center and where three-phase systems differ.

Most data centers — whether single-phase or three-phase — start by receiving high-voltage three-phase power from the electrical grid. From there, power is distributed to the remote power panel (RPP) before flowing to the server racks.

It is at this point where the processes diverge. In traditional single-phase data centers, the rack PDU transforms the three-phase power to single-phase power before distributing it to the IT equipment within the racks. The single-phase AC power is then converted to low voltage 48V or 56V DC power for usage by the IT equipment within the rack (usually between 1V DC to 12DC at the board level).

In a three-phase data center, the three-phase power continues to flow through the PDU and into the rack-mounted PSUs. It is only at the PSUs where the three-phase power is converted into low-voltage DC power that supplies the IT equipment. By running the three-phase power all the way to the PSUs, the PSUs can take advantage of the additional power capacity of three-phase while still being able to utilize the existing wiring and circuit protection (breakers).

There are multiple advantages to this approach, including:

What Is an Example of a Data Center with Three-Phase Power?

Three-phase data centers are growing more common for large commercial applications as power demands increase. One notable example is Meta, which led an exploratory initiative for the Open Compute Project that eliminated the stepdown transformers within one of their data centers. The goal was to reduce power conversion losses.

To achieve this goal, Meta eliminated the step-down transformers that reduced voltage from 480VAC to 208VAC within one of its data centers, permitting three-phase power to flow deeper into the power distribution system. The team also implemented additional custom-designed efficiency measures, such as a ductless air distribution system and the elimination of the uninterruptible power supply (UPS). The result was a data center that used 38 percent less energy to do the same work as their existing facilities, while costing 24 percent less.

What Are the Challenges of Adopting 480VAC Three-Phase Power Architectures?

There are challenges to adopting three-phase power that information and communication technology (ICT) design engineers must consider. Most of these challenges stem from the fact that three-phase architectures are less common than standard single-phase architectures, leading to compliance concerns and less equipment availability.

The challenges include:

• Lack of Standards: Three-phase power architectures are less common, so design engineers will confront a lack of industry standards when implementing this architecture.
• Difficult to Retrofit: Three-phase power architectures are more practical to implement in new data centers than in existing ones. Established data centers may not be able to take full advantage of three-phase benefits — such as smaller cables — without costly retrofits. Some equipment may also be incompatible with higher voltages, requiring replacement. On the other hand, existing wiring, breakers, and connectors should be mostly compatible if the voltage is not stepped down, as these components are typically amperage-dependent rather than voltage-dependent (up to a certain voltage limit — commonly 600V).
• Best for Large Data Centers: Three-phase power architectures are increasingly common for enterprise data centers and hyperscale facilities. However, very small data centers may not have access to three-phase power from the utility grid, making implementation impractical. Additionally, in co-location facilities with multiple clients, the different power requirements of each company could create challenges in adopting a more specialized power architecture that runs three-phase power to the PSUs.
• Safety Concerns: Increasing the voltage from 250V to 480V in the rack raises the risk of serious or fatal injuries to personnel if an electrical shock or arc flash occurs. Proper safety procedures for data center equipment maintenance (PPE, lockout-tagout, arc flash training, NFPA 70E guidelines, etc.) should always be observed and can help reduce the risk.
   

What to Consider When Adopting 480VAC Three-Phase Power Architectures

One final challenge for adopting 480VAC three-phase power architectures is the limited availability of equipment rated for higher voltages. The rack power distribution and power supplies must be designed for both the output and input of three-phase power.

Likewise, the cabling and connectors used must support the multi-phase throughput and be sized appropriately to work within the space limitations of the data rack. This can be a challenge since there are few standard source plugs and appliance connectors available for three phase power and even fewer that can accommodate a 480VAC rating. 

Typical industry connectors and their associated power outputs include:

• C13/C14 Connectors: A standard C13/C14 supplies 2.5kW of single-phase power and up to 10A of line-to-neutral support.
• C19/C20 Connectors: A standard C19/C20 is larger than C13/C14 connectors to supply more amperage. A standard C19/C20 supplies 4.0kW of single-phase power, or up to16A of line-to-neutral support.

Neither solution provides enough power to be used with 480VAC three-phase power. When the right combination of equipment and connections are found, however, the power advantages are significant. An emerging solution does offer the capability needed to meet the power and voltage requirements of 480VAC three-phase power, delivering 6.65X the power output of a standard C13/C14 in the same space.

A High-Voltage Three-Phase Connector Solution: Saf-D-Grid® Three-Phase

The brand-new Saf-D-Grid^® Three-Phase Power Cord and Connector from Anderson Power^™ is a C13/C14-sized connector rated for up to 20A, 480V line-to-line, and 277VAC line-to-neutral. This Anderson electrical connector supplies 16.63kW of three-phase power — or 6.65X the power of a standard C13/C14 — within the same compact footprint. Even compared to a C19/C20 connector, the Saf-D-Grid Three-Phase provides 4.16X the power while occupying less space.

Within a data center power train, the Saf-D-Grid Three-Phase can be used anywhere where amperages are 20A or less (16.63kW or less). The applications include connecting the PDU to the switch, the PDU to the server, the PDU to storage, the PDU to the maintenance bypass, the UPS to the maintenance bypass, the maintenance bypass to utility power, and more.

Other features of Saf-D-Grid Three-Phase and the complete Saf-D-Grid family include:

• High Thermal Rating: Saf-D-Grid is ideal for hot-aisle environments with a thermal rating of up to 105°C, providing greater headroom for conducting current in higher ambient temperature environments. Most standard connectors offer a 70°C rating.
• Integrated Latch: A mechanical tab on the connector prevents accidental disconnects by requiring a button press to disengage, avoiding power loss to critical equipment.
• Ground Contact: The ground pin is longer than the two live contacts to mate first and break connection last, providing the safety of an earthing path before engagement.
• Touch-Safe/Shock Protection: Saf-D-Grid minimizes the risk of accidental contact with hazardous voltage by passing the UL and IEC finger probe (plug and receptacle) and 3mm probe tests (receptacle).

For data centers looking to support higher voltages while saving space and cable costs, Saf-D-Grid Three-Phase provides a superior power density advantage.

Moving Data Centers Into the Future: High-Voltage Architectures

As power demands escalate, data centers must evolve. The industry’s future might just involve a shift toward high-voltage architectures, enabling data centers to maximize power and meet the future of computing demands.

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