Date: Mon, 1 Dec 2014 08:43:48 -0800 From: Mike Starr <starrtennis@gmail.com> To: Paul Pathiakis <pathiaki2@yahoo.com> Cc: John Johnstone <jjohnstone@tridentusa.com>, freebsd-questions@freebsd.org Subject: Re: UPS for FreeBSD Message-ID: <CABhTyc8ASzy_o%2BByJu=pRyc24n2QVq_g4N=07EEkVYfSy%2BxUrg@mail.gmail.com> In-Reply-To: <547B41BE.20700@yahoo.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> <54789AF3.7090100@yahoo.com> <547AAC20.1050006@tridentusa.com> <547B41BE.20700@yahoo.com>
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unsubscribe webmaster freebsd-questions@freebsd.org On Sun, Nov 30, 2014 at 8:11 AM, Paul Pathiakis via freebsd-questions < freebsd-questions@freebsd.org> wrote: > To all that responded on this thread: > > Thank you. I feel I have a better understanding of all this now. :-) > > The time spent to better educate others and myself is welcome and so > "FreeBSD Community". > > P. > > On 11/30/2014 00:33, John Johnstone wrote: > >> I agree this thread is extremely long so I'll consolidate. >> >> On 11/28/14 10:55 AM, Paul Pathiakis via freebsd-questions wrote: >> >>> Again, these UPSes are not double sine wave, they are stepped. You can >>> get one for cheap, but, again, how much value do you place on your >>> server and the information it has? If you're looking at APC, you have >>> to look at their 'server class' UPS. They start (I think) at 1500VA an= d >>> about $850. >>> >> >> I think things could be clearer about the terms "double sine wave" and >> "stepped". I think it should be made clear that although a UPS that >> outputs a 60 Hz square wave is producing a poor approximation of a sine >> wave, better designs still produce a sine wave in a stepped fashion, jus= t >> with a higher number of steps. One that produces an infinite number of >> steps would be indistinguishable from a pure sine wave. >> >> On 11/28/14 5:04 PM, Paul Pathiakis via freebsd-questions wrote: >> >>> I found this which seems to be pretty solid. I believe it someone >>> mentioned UltraUPS. >>> >>> http://www.controlledpwr.com/whitepapers/uutopla1.pdf >>> >> >> This whitepaper refers to the stepped approximation of a pure sine wave >> in their design: >> >> "The inverter reconstructs a sinewave from the DC using PWM (pulse width >> modulation); a method that =E2=80=9Cdigitizes=E2=80=9D the DC into vario= us width pulses >> to make an AC sinewave." >> >> The number of steps needs to be high enough to not cause problems. >> >> On 11/27/14 2:25 PM, Darren Pilgrim wrote: >> >>> Sine-wave approximating inverters do bad things to any power supply >>> with a regulator cap (which is everything that won't catch fire on >>> its own). The issue is the high frequency components and the >>> hundreds of under- and over-voltage events per second inherent to the >>> stepped square waveforms used (every step is a spike or sag). >>> >>> UPS manufactures know this is bad, so they try to hide it by calling >>> it "modified sine wave", "quasi sine wave", "simulated sine wave", >>> "PWM sinewave", etc., and hope you're dumb enough to fall for it. I >>> have yet to see a consumer UPS that doesn't do this. >>> >> >> I wouldn't say it fair to interpret UPS manufacturer's descriptions of >> their methods of simulation as "hiding". >> >> You need to buy a server-grade UPS to get something that won't damage >>> your electronics. APC SmartUPS, Cyberpower PFC Sinewave or Smart >>> App, Eaton 5P/PX or 9 series, Tripp Lite SmartOnline, etc. >>> >> >> On 11/28/14 1:22 PM, Paul Pathiakis via freebsd-questions wrote: >> >>> "Simulates" utility power. This is the sneaky little bit of >>> marketing. Saying it's sine output.... It is, but it's simulated. >>> I've been roped in by the APC marketing machine previously. >>> >> >> As far as "simulated" being a bad thing, by definition all UPS's have to >> simulate a sine wave once the AC power goes away. It is just a question = of >> how close an approximation is it. There's no question that a 60 Hz squa= re >> wave would be a poor approximation. >> >> As the number of steps increases, the magnitude of the "high frequency >> components" and "under- and over-voltage events" becomes so small as to = be >> negligible. There are plenty of "server-grade" UPS's that produce a ste= p >> approximated simulated sine wave as the Controlled Power whitepaper stat= es. >> >> One aspect to consider is that if a UPS isn't an on-line design, any >> negative effects experienced by the load due to the quality of the outpu= t >> sine wave will only occur when the output is being produced by the UPS >> during a power failure. It's reasonable to expect that this is going to= be >> a short interval which in many cases may not cause any power supply >> problems. >> >> - >> John J. >> _______________________________________________ >> freebsd-questions@freebsd.org mailing list >> http://lists.freebsd.org/mailman/listinfo/freebsd-questions >> To unsubscribe, send any mail to "freebsd-questions- >> unsubscribe@freebsd.org" >> > > _______________________________________________ > freebsd-questions@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-questions > To unsubscribe, send any mail to "freebsd-questions- > unsubscribe@freebsd.org" >
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