Summary: This unit is unable to keep my computer running in the case of of a power interruption. Tech support explained that this unit can not react fast enough to keep the computer running. I was advised to upgrade to the smart series which is supposed to react faster. I figured a Pro series product would handle pro grade use. Therefore, I call it dumb if it's not pro and it's not smart it must be dumb and useless.
Unmarketed inverter design is a step down in product quality.
5 June 2012
Summary: Unsuitable for sensitive electronics. Shame on APC for not communicating the transformerless design. Downgraded rating to 2/5 stars. UPS is transformerless. *GASP* An inverter continuously supplies power during both backup and mains power. My readings on the oscilloscope show worse quality than former models. I guess computers and other transformer-powered electronics should be fine, but I suspect damage is possible.
Summary: After first purchasing this product, I noticed the fan would come on, and stay on for hours, even if the power loss was momentary ( less than 30 seconds). I have not heard of any other UPS equipment doing this. As a preface, I have a data center with over $20K of APC Symmetra backing it up. I have also used larger APC tower units for years, and none of them had fans that would run continuously after only a monentary power event.
Summary: Don't buy this product if you expect the unit to be quite. The fan kicks on alot and seems to never shut off so an office environment it is unacceptable. Here is a link discussing the issue on the APC forum[...] Since mine is in a room where my servers are noise isn't a issue.