Date: Thu, 17 Oct 2013 09:38:20 +0800 From: Erich Dollansky <erich@alogt.com> To: Frank Leonhardt <frank2@fjl.co.uk> Cc: freebsd-questions@freebsd.org Subject: Re: UPS buying suggestion Message-ID: <20131017093820.6a8428de@X220.ovitrap.com> In-Reply-To: <525F0138.1020304@fjl.co.uk> References: <CACo--msUpY-6r7MkuEvrPDpSVdFZyBotSA-eS7aLGMFDeq_vDQ@mail.gmail.com> <alpine.BSF.2.00.1310150911510.97788@wonkity.com> <CACo--mvUfcAy=0hyun21DZwSmdd=SmP7EeU-FVxJyiT_h4Rxkg@mail.gmail.com> <525F0138.1020304@fjl.co.uk>
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Hi, On Wed, 16 Oct 2013 22:12:24 +0100 Frank Leonhardt <frank2@fjl.co.uk> wrote: > On 16/10/2013 03:43, yudi v wrote: > > At the risk of going off-topic: as Warren has pointed out, not all > UPS units are the same. In fact, many units calling themselves a UPS > are actually backup power supplies, which switch over to battery if it is a rare event to see the on-line version here. Of course, they are much better when it comes to wave form and switch-over time. The wave form is very close to a sine wave and they do not have to switch over as they are always providing the power. But you also must see the cost. You loose about an extra 10% of electricity in the system. So, it is also a cost factor. > the mains fails. Common usage definitions vary, but to my mind, in > USP the output should be supplied by the battery all the time, while > the mains constantly recharges, so there is no switch-over > whatsoever. The quality of the mains voltage they produce also varies > - it might be a pure sine wave (as if the mains always was!), or it > might be something else. If it's going through a switched-mode power > supply afterwards I don't see this as a big issue - the only thing > I'm worried about is whether it keeps the computer (HP Microserver - > back on topic briefly) running when Gonzo does something to the > mains. Audio amplifiers and radio equipment might be another matter, > but the switcher found in practically every computer does such > unspeakable things to the input mains anyway I can't get to excited > about how close to a sine wave the output actually is. As long your music source is not connected to the UPS. In addition, water pumps and hair dryers have an akward sound when it is not a sine wave. Ok, hair dryers are not important. Lights also go brighter when it is not a sine wave. Yes, there are strange things connected to an UPS if you live in some locations. Erich
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