[GLLUG] UPS trouble

[Tom Schouten]

Hi list,

I recently purchased a UPS unit: APC Back-UPS ES BE550G 8-Outlet 550VA 120V

The main use is to bridge circuit breaker triggering since we're close 
to maximum load on some of the lines in the house with the AC units 
running.  I.e. I need about 5 minutes to pick up a flashlight and head 
to the basement.

It seems to work well for my setup when the power cuts out, however when 
it turns back on there are glitches.  My PC is able to bridge the glitch 
when I put it to sleep mode, but my IP phone seems to reset or hang and 
the PC resets when it is running.

The unit supports 350W and the max load I've measured is 200W.  The 
glitches happen even with a load of about 40W = just the PC.

Any ideas what this might be?  Is this a known property of these cheap 
square-wave approximate sinusoid boxes?

Cheers
Tom