Re: Generators and switch mode power supplies.
- From: JosephKK <quiettechblue@xxxxxxxxx>
- Date: Thu, 12 Feb 2009 08:17:34 -0800
On Thu, 12 Feb 2009 17:54:02 +1100, Sylvia Else
<sylvia@xxxxxxxxxxxxxxxxxxx> wrote:
JosephKK wrote:
On Sun, 08 Feb 2009 23:30:44 +1100, Sylvia Else
<sylvia@xxxxxxxxxxxxxxxxxxx> wrote:
Nico Coesel wrote:
Sylvia Else <sylvia@xxxxxxxxxxxxxxxxxxx> wrote:I assume that's related to the harmonic load represented by switch mode
Given the parlous state of Australia's power systems, I've beenNot really. A computer doesn't care much as long as the voltage is
considering buying a standby generator. One marketing point of some of
the inverter based models is their suitability for 'sensitive
electronics' with computers given as an example. This appears to be
based on the fact that they'll provide a consistent sinewave output.
But given that computers invariably use switch-mode power supplies, are
they actually going to care what waveform they see - from square wave
thru 'modified sinewave' thru pure sinewave?
within range. One thing to consider is that computers are a bad load
to a generator. As a rule of thumb you need a generator with at least
twice the VA rating as the total VA rating of all computers. Otherwise
the generator cannot keeps its rpm constant (starts speeding up and
slowing down).
power supplies.
Circuits for significantly improving the harmonic performance have been
around for a decade, but I suppose little will happen until legislation
requires their use.
Sylvia.
May not have happened yet down there, but has been around for about 2
decades in the US now.
I came across this
http://www.enhanceusa.com/designguide/atx12v_v2.0.pdf
which doesn't mention any US requirements, but does refer to some
European and Japanese ones.
This document gives details from EN 61000-3-2.
http://www.reo.co.uk/files/handbook_en_61000-3-2.pdf
The class D limit of 3.4mA/W for the third harmonic means 1.7A for a
500W (input) PS, which would be drawing only just over 2A at the
fundamental.
Doesn't seem an exactly onerous requirement. Indeed, I'd have to wonder
what an uncorrected 500W SMPS would be drawing. Have lobbyists managed
to get the standard set so that manufacturers actually had to do nothing?
Sylvia.
It certainly looks like they did, at least partially:
http://www.epsma.org/pdf/PFC%20Guide_April%202005.pdf
http://archive.evaluationengineering.com/archive/articles/0900deal.htm
All on the first page of results of a search for:
en_61000-3-2.
.
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- From: Sylvia Else
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- From: Sylvia Else
- Re: Generators and switch mode power supplies.
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- Re: Generators and switch mode power supplies.
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