> From: [email protected] [mailto:[email protected]] > On Behalf Of Doug Hughes > > > I continue to wonder why more data centers don't use -48V DC > distribution. > > > Because it would hugely expensive in terms of copper. to deliver 200W at > -48V DC requires copper capable of carrying 4A. To do so at 208V > requires a cable capable of 1A
Which is more expensive? You run AC to your UPS, convert it to DC, convert it back to AC, deliver it to your systems, and convert it to DC again... Or You run AC to your big UPS, and deliver 48V DC to all your systems using 4A wire. By using your 4A wire, you're able to eliminate the D2A, and all the A2D's in all the systems. I think the wire is cheaper, at least in theory. The real question is ... How popular is it? If it's insufficiently popular, then the prices will be unnecessarily high. And that's all there is to it. If only the DC standards were more widely adopted, this would be a very clearly beneficial winner. Not so much in terms of energy savings (assuming you were going to use well-designed D2A's and A2D's, you only have a few percent energy loss in the power conversions) Mostly the benefit is in terms of hardware. Not needing to buy all those computer power supplies. As-is today, only some of the largest server facilities are deploying DC power to their systems. Because they're the only ones who have a scale large enough to make it worthwhile. _______________________________________________ Tech mailing list [email protected] https://lists.lopsa.org/cgi-bin/mailman/listinfo/tech This list provided by the League of Professional System Administrators http://lopsa.org/
