On Fri, 30 Aug 2019 14:02:26 +0000, Bob Eager wrote:

On Fri, 30 Aug 2019 12:40:51 +0100, T i m wrote:

Can that not depend on the UPS though? Some do provide some passive
filtering but only produce any output themselves when the power fails
('Offline').

Others are more as you describe where they are maintaining the output
themselves all the time and so can do as you say ('Online').

No, there are online ones that adjust the output voltage to keep it in
spec. The APC SmartUPS series do that (I have three).

They electronically adjust the taps on a transformer (probably an
autotransformer, I've never looked) to trim over-high voltages and boost
low ones. If it goes too out of spec, then it'll switch to battery to
keep it going.

This is one of the reasons I use the UPSs - round here we seem to get a
lot of voltage fluctuations.

Sorry, my first sentence should have said 'offline' of course. Runs with
the mains unless it goes way out of spec or fails, then uses battery.



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