Hi folks, I'm looking at several brands of rackmount 3kva double-conversion UPSes, such as Tripp Lite and Eaton Powerware. I'm specifically looking for something that will work as a line-interactive UPS until the power starts to misbehave and will then switch to double-conversion mode until a while after the last power bump. Basically I want the best of both worlds: save money on my power bill most of the time (double-conversion UPSes generally waste 10%-15% of the consumed kilowatt hours) but switch to nice clean double-conversion when the storms roll through and the power gets rough. Here's where I'm looking for help: the vendor web sites have scanty details about how the UPSes behave in their high efficiency modes. I'm hoping folks here have used some of the UPSes with this feature and can offer feedback. When does the UPS decide to switch to double-conversion? When does it decide to switch back? Are the options tunable? Through what interface? Can I write software that monitors a weather report and sends an SNMP message to switch the UPS to double conversion mode ahead of a storm? Eaton's 9130 says "On the High Efficiency setting, the UPS operates normally on Bypass, transfers to inverter in less than 10 ms when utility fails, and transfers back to Bypass in 1 minute after utility returns. The indicator illuminates when the UPS transfers to Bypass." http://lit.powerware.com/ll_download.asp?file=Eaton%209130%20UPS.pdf Tripp Lite's SU3000RTXL3U only says "If the UPS has been placed into Economy Mode (available on select UPS systems), it configures an online UPS to function as a switching UPS. When the UPS system is in Economy Mode, it operates at increased efficiency while AC utility power is available (within +/- 10% nominal) and switches to battery power if AC utility power is interrupted." http://www.tripplite.com/shared/techdoc/Owners-Manual/932471.pdf What others should I consider? Can anyone offer details? Thanks, Bill -- William D. Herrin ................ herrin@dirtside.com bill@herrin.us 3005 Crane Dr. ...................... Web: <http://bill.herrin.us/> Falls Church, VA 22042-3004