In article om,
Dave Liquorice wrote:
On Wed, 01 Sep 2004 09:25:50 +0100, Dave Plowman (News) wrote:

You can run a cooker off a UPS? Good grief...

Well my small APC one will chuck out 700W but not for long about 3 or
4 mins from it's internal 7A/hr batteries. 1.5kVA UPSs aren't that
much more expensive, the limitation is the energy storage, I've
somtimes thought about getting a couple of good sized leisure
batteries for my UPS just to up the runtime, it's calculation of
runtime will be up it but I could live with that.

I've used and installed various UPSs over the years (in my IT capacity)
and the general rule seems to be that on a standard unit you'll get 15
miuntes at half load. It's more or less linear at less loads than that
(eg. 30 miuntes at 1/4 load) but more than half load it's non-linear. Down
to 5 or 6 minutes at full load. This seems to be a reasonable general
rules I've seen with different makes (although I prefer APC ones)

Of-course the extended range ones offer more run-time, but ...

Gordon