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Power Distribution Shakeups: Evaluating Your Voltage Options

If you’re in North America like 1547, you’ll be evaluating your data center power based on the 480/208/120 V three phase scheme.

Our facilities’ transformers step down the much higher voltage delivered from the utility to one of these phases for your distribution. As densities increase and designers start to build out in a scaling, modular fashion, different distribution methods and voltages are gaining appeal. Here are some of the major options for distributing power in your data center.

Power Distribution Levels and Transformers

 Before power reaches the rack, it must run through the UPS and any other distribution equipment. At this stage it is likely to still be 480 V, especially for larger data center floors. However, smaller scale deployments can distribute at 208 V or even 120 V. If you don’t anticipate higher power draw in the future, this could save some money on equipment and cabling.

If distributing at 480 V, you’ll need transformers on the floor to Step Down the voltage to 208 or 120 V, depending on the need. Transformers can be pricey but deliver significant energy savings, as each transformation will result in a slight loss.

A 208 V distribution system does not need to be transformed, unless you’re concerned about imbalances from the UPS. Fluctuations can damage IT equipment, but this isn’t always a major issue.

Higher voltages translate to lower currents needed for your power delivery requirements. Ultimately that means higher voltage, lower amperage, and smaller, less expensive equipment. A great upgrade to make to your data center, assuming your power switches and paneling is up to the task, would be increasing the size of your feeder cables to carry 480 V, as they can then deliver more power over the same length.

Increased Density and Three Phase Power

With a mere 20-40 amps required for a 2 kW rack, older data centers were set with just 120 V. Now, 10 kW is common, and deployments can reach much higher densities, meaning 230V is often required even at the 5 kW level.

By running three phase power direct to the rack, you can increase efficiency and also deliver significantly more available power. It also allows you to run older equipment that only needs 120 V while simultaneously powering 208 V equipment, all on the same feed.

This is all only to focus on the United States standards—Europe has different standard voltages, which can be used in concern with American equipment as well. Ultimately, your power distribution will depend on a combination of existing equipment, future density plans, and current power requirements, as well as the skills of your IT staff.