tech wrote: > John R Pierce wrote: > >> all the BackUPs I've ever seen have been simple relay switched units. >> when the power is on, you're getting unfiltered power (except for a MOV >> based surge protector), when the power is out, it switches to the >> "modified square wave" inverter output. >> > > John, > > There are units that change the AC to DC. The DC then charges the > batteries and gets changed back to AC for the equipment. These units are > very expensive though. > There are online UPS, as you describe. I don't believe any of them have the APC BackUPS brand name on them. I don't even think APC SmartUPS are online, however as I said, the SmartUPS do have power conditioners.