Re: UPS sine wave vs square wave output?

From: jsmith (juddo_at_ix.netcom.com)
Date: 02/23/05 

Date: Wed, 23 Feb 2005 01:14:03 -0500

"John Tserkezis" <jt@techniciansyndrome.org.invalid> wrote in message
news:421c14e5$0$31622$afc38c87@news.optusnet.com.au...
> jsmith wrote:
>
> >>> Why such insistence on a UPS having a "pure" sinewave vs any other
sort
> >>> of output wave form such as square wave?
>
> >>Because the power supplies in the equipment it is powering have all
> >>been designed to accept a sine wave from the mains supply. There is no
> >>guarantee how they would behave when presented with a square wave.
>
> > How does one design a power supply to accept a sine wave but not a
square
> > wave??
>
> You don't. Not intentionally anyway.
>
> A square wave input of the same RMS value of an equivalent sine wave
will
> have a much higher crest factor. That is, the peak value is *much* higher
in
> relation to the RMS value, as compared to a sine wave.
>
> Most power supplies simply bridge rectify the AC input, and feed that
> somewhat pulsating DC into the regulator that does the bulk of the work.
>
> With a sine input, that peak DC at the filters will be 1.4 times the
sine RMS
> value.
> With a stepped square wave, or worse still, a pure square wave input of
the
> same RMS value as your sine input will have a peak much higher.
>
> Thus, if your components are only expecting a peak of X volts, and you
force
> feed it something significantly higher than X, it'll blow.
> --
> Linux Registered User # 302622
<http://counter.li.org>

So why not lower the peak voltage of the square wave to a safe level??

Relevant Pages

  • Re: UPS sine wave vs square wave output?
    ... >> How does one design a power supply to accept a sine wave but not a square ... > With a stepped square wave, or worse still, a pure square wave input of the ...
    (sci.electronics.design)
  • Re: Square to Sine Wave
    ... put out a pure sine wave are expensive. ... wave inverters use variable pulse width modulation to closely ... Starting with a square wave at some considerable power level, ...
    (sci.electronics.design)
  • Re: resonant frequency
    ... wave at a resonant frequency have the same effect as a sine wave at ... A sine wave at one frequency is better approximated ... In the case of a square wave, what you need to know is what collection ... But you can analyze the circuit in terms of each continuent ...
    (sci.electronics.basics)
  • Re: resonant frequency
    ... For instance, will a square ... wave at a resonant frequency have the same effect as a sine wave at ... What happen is that the resonance sorta picks out the frequency of the ... This is a sine wave that we get. ...
    (sci.electronics.basics)
  • Re: Interpreting Square Wave Traces
    ... square, and a wave, at the same time. ... From a practical point of view, a "square wave test" confuses the response ... recording studio, or had the opportunity to talk at length to the ... Most session musicians, including orchestral players are ...
    (rec.audio.tubes)