Greening the data center: The voltage wars …

I’ve just been reading about Server Tech promoting 415V power for data centers. This is another shot in the long running struggle for efficiency that I think has a far simpler answer, so I’ll revisit the topic here.

The key to voltage and efficiency is simple, use the highest possible voltage that will work directly with the load and not require transformers. This reduces the loss from cable resistance and multiple steps of transformer. Keep in mind, I’m a strong proponent of DC power distribution, but I’m only going to address AC here.

The standard industrial voltage format in the US is 480Y277. This format provides 480V 3 phase and 277V single phase power. This format is great for equipment such as large DC power plants that are designed to use the 480V directly, however, the 277V is virtually useless except for industrial lighting fixtures (which is what it was designed for).

Most “universal” type power supplies are designed to operate anywhere from 90-250V. This has produced the call for odd voltages such as 600V to 208Y120, 400Y230, and 415Y240. These are all generally foreign formats and not found in the US.

There are two simpler solutions to this. The first solution is to use US standard 240D power. This is an older but still common industrial standard, provides power at the top of the range for “universal” power supplies, is compatible with lower cost PDU equipment, is easy to distribute, and does away with the rarely used high voltage component.

The second solution is to join the push to encourage manufacturers to extend the “universal” power supply voltage window to 277V. Now the standard 480Y277 is fully usable without resorting to crazy foreign power formats.

Or you could just go with a nice green DC power system, get the maximum in efficiency benefits, and forget the AC voltage wars altogether.

Vern, SwiftWater Telecom

data center, web hosting, Internet engineering


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