UPS Recommendations

Michael Torrie torriem at
Fri Aug 27 08:04:09 MDT 2010

On 08/27/2010 01:56 AM, Shane Hathaway wrote:
> So, for a time, the UPS generates power at a slightly incorrect 
> frequency in order to adjust the phase?  That's a cool hack.

That's my understanding.  The generator is generating a standard 60 Hz
sine wave on each of the three phases.  The problem is that the
generator's phase is never going to be the same as the line's.  So the
UPS slowly (well, quickly actually) shifts the phase by slightly
altering the frequency until it matches the generator's.  Then when the
line power comes back, it has to shift to match the line's phase.

> I prefer the idea of putting batteries in the computer, though.  It 
> works for laptops, why not for servers?

Line UPS works for *everything*, which is why it's can be appealing for
data centers.  Covers the servers, switches, monitors, heating and
cooling, lights, etc.

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