There's a lot of misinformation out there regarding generators, UPS', sine waves, etc. I'd just like to clarify some things. First, in general, generators and UPS' do not get along nicely. Most low-end UPS' are so-called "standby" or "backup" UPS' in that their inverters are not running all the time. The rest of the time, they just pass the utility voltage right on through to the connected equipment (perhaps with some conditioning of the voltage). This type of arrangement with a typically underpowered generator (<10kW) and a standby UPS will cause the UPS to cycle from line to battery repeatedly until the battery dies, all while creating lots of noise on the AC side. (If you do get it to sync, it would be like connecting your equipment directly to the gennie with a power conditioner in between).
One solution to this problem is to use an oversized generator (>10kW). This means $$$$$$$$$$$ which a lot of us don't have. So we go out and do the best we can with what we have and that's likely a cheaper construction-grade generator, maybe around 5-7kW and about $500-$1000. That'll run just about everything you need it to in most houses, except for the well pump if applicable. And remember this generator will put out DIRTY AC that's poorly regulated (think +/- 3Hz on frequency) and have lots of harmonic voltage distortion. This is OK for most things except sensitive electronics.
Which brings us back to UPS'. The type of UPS you need to run off a generator is what is called an "online" or "double-conversion" UPS. This type of UPS always converts the incoming AC to DC then back to true 120V / 60Hz AC. THIS IS THE ONLY WAY TO CORRECT FREQUENCY. These units are not cheap as you may have imagined.
I have one of these (APC SURTA1500XL):
http://www.apc.com/resource/include/techspec_index.cfm?base_sku=SURTA1500XL
That I use for the bulk of the electronics I use off the generator including TV, DVR, PC, receiver, etc. I bought this after the ice storm of 2008 that knocked power out for eight days. It cost roughly $1000.
I also have one of these (CyberPower OL1000RMXL2U):
http://www.cyberpowersystems.com/products/ups-systems/smart-app-ups/paragon-series/OL1000RMXL2U.html
That I used for the pellet stove. I figured same type topology of UPS, significantly cheaper...should be good, right?
After going through two days without utility power, but with a backup generator (http://www.homelite.com/catalog/generators/HG5700), I can say that the APC unit is built to a much higher standard (and it costs more too unfortunately). The TV and everything worked flawlessly with the APC, but after two days of running the pellet stove off the CyberPower, I could hear the motors sounding differently. I'm now purchasing an additional APC SURTA1500XL exclusively for the pellet stove and I'll move the CyberPower for a different use.
Remember that this type of UPS ALWAYS regenerates the true 120V / 60Hz that is needed for its output and ALWAYS accepts whatever crappy AC you feed it on the input. And it'll also run your equipment off battery for awhile if you lose all power...
I also have to throw in a warning that if you connect a generator to a building's wiring, you MUST use a transfer switch or you could face extensive fines or even kill a line worker.
One solution to this problem is to use an oversized generator (>10kW). This means $$$$$$$$$$$ which a lot of us don't have. So we go out and do the best we can with what we have and that's likely a cheaper construction-grade generator, maybe around 5-7kW and about $500-$1000. That'll run just about everything you need it to in most houses, except for the well pump if applicable. And remember this generator will put out DIRTY AC that's poorly regulated (think +/- 3Hz on frequency) and have lots of harmonic voltage distortion. This is OK for most things except sensitive electronics.
Which brings us back to UPS'. The type of UPS you need to run off a generator is what is called an "online" or "double-conversion" UPS. This type of UPS always converts the incoming AC to DC then back to true 120V / 60Hz AC. THIS IS THE ONLY WAY TO CORRECT FREQUENCY. These units are not cheap as you may have imagined.
I have one of these (APC SURTA1500XL):
http://www.apc.com/resource/include/techspec_index.cfm?base_sku=SURTA1500XL
That I use for the bulk of the electronics I use off the generator including TV, DVR, PC, receiver, etc. I bought this after the ice storm of 2008 that knocked power out for eight days. It cost roughly $1000.
I also have one of these (CyberPower OL1000RMXL2U):
http://www.cyberpowersystems.com/products/ups-systems/smart-app-ups/paragon-series/OL1000RMXL2U.html
That I used for the pellet stove. I figured same type topology of UPS, significantly cheaper...should be good, right?
After going through two days without utility power, but with a backup generator (http://www.homelite.com/catalog/generators/HG5700), I can say that the APC unit is built to a much higher standard (and it costs more too unfortunately). The TV and everything worked flawlessly with the APC, but after two days of running the pellet stove off the CyberPower, I could hear the motors sounding differently. I'm now purchasing an additional APC SURTA1500XL exclusively for the pellet stove and I'll move the CyberPower for a different use.
Remember that this type of UPS ALWAYS regenerates the true 120V / 60Hz that is needed for its output and ALWAYS accepts whatever crappy AC you feed it on the input. And it'll also run your equipment off battery for awhile if you lose all power...
I also have to throw in a warning that if you connect a generator to a building's wiring, you MUST use a transfer switch or you could face extensive fines or even kill a line worker.