[iyonix-support] Re: UPSs and reflashing the ROM
- From: Dave Higton <davehigton@xxxxxxxxxxxxx>
- To: iyonix-support@xxxxxxxxxxxxx
- Date: Sat, 28 Oct 2006 22:04:28 +0100
In message <4e7ce312deJeremy@xxxxxxxxxxxxxxxx>
Jeremy C B Nicoll <Jeremy@xxxxxxxxxxxxxxxx> wrote:
> So, I'm wondering if I should buy a simple UPS. Can anyone recommend
> one? What sort of VA rating? One I've seen was described as having -
> I think - something like a 300W 500VA rating - how come the W figure
> isn't the same as the VA one?
Power supplies present loads (to the mains) which are not purely
resistive. On each quarter cycle of the mains, some current is
taken from the mains, part of which is returned to the mains in
the next quarter cycle.
Ideally, consuming equipment like the Iyonix should have a spec
somewhere for both the power and the VA rating. The VA rating
can never be less than the power rating, and is usually quite a
bit more (but I've never seen any equipment where the factor is
as much as 2).
You need to add up /both/ the power rating and VA rating of all
the pieces of equipment that you intend to run off the UPS, and
make sure that both of them come within the appropriate rating
of the UPS.
There is an interesting debate to be had about whether a UPS
increases or decreases the reliability of a system, since, of
course, the UPS itself can fail.
Dave
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