Hi Day Brown, hope you are having a nice day
DB> If I *had* to run a computer on an inverter, I'd use an isolation 
DB>transformer, and hope the hysteresis would damp the ripple in the 
DB>sin wave from the inverter, and pick up the slack when the SWPS 
DB>IGBT shuts on/off.  Of course, isolation xfmrs are big, expensive, 
DB>and heavy. 
 Dunno about that. I've seen iso-xfrmrs for under $50US with 2KW
ratings. Besides, why go to all that trouble. A ups with a ferroresonant
xfrmr doesn't have that problem. The xfrmr has a secondary winding with
a cap that's resonant to the xfrmr. End result? No funky waveforms
on the output. Pure sinewave, no glitches during zero crossing or
when the drive is switching polarity. Even when fed from triangle
or mod-sinewave.
 I've a 1600W that needs batteries and the pinout for the DB-15
connector in back, that has a ferroresonant. Plus the 2 main
xfrmrs (2KW total give or take) from an IBM mini that are the 
same type.
 They'll cost you a bit more, but you'll *never* see when they 
switch over to/from run mode. Plus if there's any noise in the
Incoming power, that's removed too.
 -=> Yours sincerely, Paul Williams <=-
... "Medication is Futile." ;-) - Joost
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