Re: Generators and switch mode power supplies.

On Mon, 09 Feb 2009 19:42:16 GMT, Richard The Dreaded Libertarian
<null@xxxxxxxxxxx> wrote:

On Sun, 08 Feb 2009 23:30:44 +1100, Sylvia Else wrote:
Nico Coesel wrote:
Sylvia Else <sylvia@xxxxxxxxxxxxxxxxxxx> wrote:

Given the parlous state of Australia's power systems, I've been
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?

Not really. A computer doesn't care much as long as the voltage is
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).

I assume that's related to the harmonic load represented by switch mode
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.

If the idea was any good, you wouldn't have to impose it by force of arms.

Thanks,
Rich

PFC prevents fires, too. You approve of fires?

John

.

Relevant Pages

  • Re: Generators and switch mode power supplies.
    ... considering buying a standby generator. ... based on the fact that they'll provide a consistent sinewave output. ... But given that computers invariably use switch-mode power supplies, ... twice the VA rating as the total VA rating of all computers. ...
    (sci.electronics.design)
  • Re: Generators and switch mode power supplies.
    ... 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. ... twice the VA rating as the total VA rating of all computers. ...
    (sci.electronics.design)
  • Re: Generators and switch mode power supplies.
    ... 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. ... 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? ... I assume that's related to the harmonic load represented by switch mode power supplies. ...
    (sci.electronics.design)
  • Re: Generators and switch mode power supplies.
    ... 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. ... The class D limit of 3.4mA/W for the third harmonic means 1.7A for a 500W PS, which would be drawing only just over 2A at the fundamental. ...
    (sci.electronics.design)
  • Re: Generators and switch mode power supplies.
    ... considering buying a standby generator. ... based on the fact that they'll provide a consistent sinewave output. ... But given that computers invariably use switch-mode power supplies, ... Doesn't seem an exactly onerous requirement. ...
    (sci.electronics.design)
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