In Large Data Centers, Medium-voltage Distribution Makes Lots of Sense

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Data center engineers have long dealt with the issue of distributing power to the various components that need it, from CRAC/CRAH units to IT equipment and UPSs. For the most part, one or more medium voltage feeds come into the data center from the utility and from there a network of low-voltage lines, say 415 or 480 volts, distribute power to wherever it needs to go.

As data centers get larger, however, that age-old model is starting to create a great deal of complexity. Think about hyperscale data centers, which I’ll define as any data center that consumes 10MW or more of power. Typically, these are big, sprawling campus-level facilities, often run by cloud or colocation providers but also some large enterprises. The ability to distribute power at low voltages across the long distances inherent in such data centers requires multiple large conductors, along with conduits and raceways that require a lot of work to install, maintain and modify.

A better approach is to use medium voltage lines to distribute power, then step down to low voltage when you’re physically closer to whatever will ultimately consume the power. The result is a far less infrastructure-intense setup throughout the data center – resulting in less complexity. (Let’s not forget that complexity is the enemy of resilience in data center design, as other bloggers have discussed.)

Let’s say you need to distribute 1MW of power in a spacious data center. If you use medium voltage lines of 4.16kV instead of low-voltage lines of 400 or 480 volts, you need 8 to 10 times fewer wires, cables, and buses to deliver the same amount of power. That translates to a huge reduction in the amount of complexity in your data center, not only in sheer infrastructure but in terms of tasks such as switching to backup energy. It’ll be far easier to make the connections, landings, and transfers to backup power sources with so many fewer lines to deal with.

Of course the cost of the medium voltage switchgear, transformers and generators will be higher than that of low-voltage equipment. You’ll have to analyze the balance point at which it makes sense to pay the premium. But clearly when we start to talk about installations above 10MW or 20MW of power, it makes economic sense to go with medium voltage distribution equipment.

Another challenge is finding MV distribution equipment that is safe, reliable and easy enough for data center personnel to maintain. You need products that are optimized for the data center environment, with safety enhancements that ensure that qualified in-house staff can operate it without perceived risk. The products also need to provide simple maintenance over time. Schneider Electric already has medium-voltage products that support these requirements and meet International Electrical Code standards; we’ll soon have the same for the North American market meeting UL standards as well. To learn more of about these medium-voltage products, click here.

For most companies, data centers are continually getting larger. At some point, many will want to take a hard look at whether low-voltage distribution still makes sense. It’s not a transition that will happen overnight, of course, so if you’re a candidate for medium-voltage distribution, it wouldn’t hurt to start planning now.

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