Date: Sat, 29 Nov 2014 12:12:11 +0800 From: Erich Dollansky <erichsfreebsdlist@alogt.com> To: Jon Radel <jon@radel.com> Cc: Michael Sierchio <kudzu@tenebras.com>, FreeBSD Questions <freebsd-questions@freebsd.org> Subject: Re: OT: UPS for FreeBSD Message-ID: <20141129121211.014cb856@X220.alogt.com> In-Reply-To: <547937AB.1030706@radel.com> References: <CAHieY7QGp2ELF-R91eu=vSrPsimVmVNJQ4kfucQ56PR7EEZmig@mail.gmail.com> <m57qdq$did$1@ger.gmane.org> <54777AB1.9010800@bluerosetech.com> <m581p1$65m$1@ger.gmane.org> <54779629.302@bluerosetech.com> <alpine.BSF.2.11.1411271433320.60866@wonkity.com> <5478BD4F.7020306@yahoo.com> <5478BEE6.30308@bluerosetech.com> <5478CC08.9090307@yahoo.com> <20141128204722.561f948e@archlinux> <5478F16A.80605@yahoo.com> <CABhTyc9m7fOoeV170dj=foAhmyYWphzc8KD8wBacu5gNRPhT%2BQ@mail.gmail.com> <54791d3a.w/pI0kak03d%2B3nKC%perryh@pluto.rain.com> <CAHu1Y71vVbdx6Yd1VbE7kb_8k9O5UG93RXEaORPU0tULCpMsCQ@mail.gmail.com> <547937AB.1030706@radel.com>
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Hi, On Fri, 28 Nov 2014 22:04:11 -0500 Jon Radel <jon@radel.com> wrote: > On 11/28/14, 8:26 PM, Michael Sierchio wrote: > > I've always found it amazingly absurd that you use a UPS (a bank of > > batteries charged by AC->DC conversion), invert it back to AC, > > which gets converted to DC for the motherboard and peripherals. > > > > But that's just me, probably. > > Hardly. See > http://hightech.lbl.gov/dc-powering/ > https://gigaom.com/2012/01/13/the-next-big-thing-for-data-centers-dc-power/ > etc. It's not storming the world, but some are doing it. > it is just a hype with two exceptions. Real high voltage transmission lines using DC make sense. Having a DC grid locally could also make sense especially when solar power comes into the game. As all voltage conversations take place via AC, plain DC networks do not and will only very rarely exist. Even solar powered grids need AC for regulating the grid voltage. Erich
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