Date: Tue, 15 Oct 2013 15:10:43 +0200 From: Ralf Mardorf <ralf.mardorf@alice-dsl.net> To: freebsd-questions@freebsd.org Subject: Re: UPS buying suggestion Message-ID: <1381842643.757.77.camel@archlinux> In-Reply-To: <20131015201644.228f1ae2@X220.ovitrap.com> References: <CACo--msUpY-6r7MkuEvrPDpSVdFZyBotSA-eS7aLGMFDeq_vDQ@mail.gmail.com> <20131015134826.528289be@X220.ovitrap.com> <CACo--mvzj6K20YRZuXk0hCxpAvPxKQYUs-K6Te48uJ%2BXc-=8ag@mail.gmail.com> <20131015163434.5834988c@X220.ovitrap.com> <1381837542.757.45.camel@archlinux> <20131015201644.228f1ae2@X220.ovitrap.com>
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On Tue, 2013-10-15 at 20:16 +0800, Erich Dollansky wrote: > 'For what are known as "reactive loads" the answer is no. Reactive l' > > A PC is a reactive load. You're doing the measurement for a while and then you win an impression of the consumption. Reactive power compensation can reduce the reactive power, however, your electricity provider only will measure the active energy, only for large customers they will measure the reactive energy. IIUC the OP want's to get a raw impression of what is needed and isn't interested in rocket science. > > Anyway, you can't trust those power meters. > > Do not think so bad. It is all a matter of price. Yes, you need a rotary current meter, like the once your electricity provider installed to your home, or you turn off everything at home, excepted of the computer and check the consumption by this meter. If you want to have more precision, ask them to install a device to measure the reactive power too ;). For electronics usually the rule of three and rule of thumb are used, by ignoring internal resistance of one or the other source, tolerances of one or the other component, phi etc. pp.. But there is more math than just the rule of three available, for theoretical usage and perhaps rocket science. Regards, Ralf
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