[ale] UPS

[Alex Carver]

On 2/6/2013 06:51, Derek Atkins wrote:
> Mike Harrison <cluon at geeklabs.com> writes:
>
>> Depending on the exact models and configuration, the difference
>> is the Tripp-lite is live, the APC is in standby and must switch on.
>> That 'cross over' from line to inverter is the flicker...
>> that you won't get on the Tripp-lite because it is already live
>> and powering your stuff.
>
> Yep, this is why I chose the Tripp-lite. I often have very short
> brown-outs which were long enough to kick into my UPSes but short enough
> that it didn't fully kick over, and I had one server that didn't like
> this.  I tried three different UPSes behind the server and while it
> always survived a "pull the UPS from the power" test, the system's power
> would always fail when I had a "real" power hit -- but the outage was
> too short for the BIOS's "turn on when power restored" feature.

Not all of APC's units are switched.  As long as you use one of the 
larger capacity BackUPS Pro, SmartUPS or any of the higher end systems 
(Matrix, Symmetra, etc.) you get always-on operation (AC-DC-AC conversion).

You can tell it's always on if it has the ability to measure load and 
estimate battery life or it can auto trim the voltage.  I have two 
BackUPS RS 1500's (not made anymore, I think it was folded into the 
BackUPS pro line) that do live switching.  I have a smaller BackUPS that 
does not do this.  The two 1500's ride out just about any flicker I 
have, even better than the all DC UPS that powers the AT&T network 
interface (made by Belkin, doesn't work for anything if you want the NI 
to stay up after a blink).