I need a little help trying to decide between Line Interactive or Online UPS. I have a 22kw whole house generator from Generac that kicks in when the power goes out. I’m in the process of building a NAS and modest home server to run a few VMs and got to thinking about uninterrupted power supplies. After researching I haven’t yet found a clear answer as to whether I need normal line interactive UPS or need the full on $$$ Online UPS to overlap the power being made by the generator? Obviously the battery part I don’t need much of just a minute of battery to let the generator ramp up. But do I need the added cost of the AC to DC to AC process to get pure sine wave power to the rack?
Generac’s documentation states the generators output is sine wave with <5% THD. That’s within the range of standard AC wall power and thereby safe for sensitive electracies if those statements are reliable.
I know I could just buy the Online and not worry about it but the price curve is steep. Anyone have any thoughts or real experience? My fear is letting the smoke out of expensive stuff.
I had a cheap, small UPS that would didn’t like generator power. The generator power wasn’t very clean, so I could understand the issue. The cheap UPS would constantly switch from battery to online- so it wouldn’t charge from the generator and eventually, the battery would die. Running it off the generator wasn’t a long term possibility.
I have a double conversion, online UPS now that has a generator mode. I don’t know if I’ve ever tried it, so I can’t say for sure. There was one time that the power went out for a few hours and we ran the generator, but I honestly can’t remember how the UPS handled that.
The generator that I have is an 8kw generac, but not the whole house kind. I think it’s an older model and I remember there was a more expensive one that advertised “crystal sync” or something like that.
I prefer double conversion because it’s not only voltage that can cause issues, frequency is another big one. I actually see frequency alerts from a UPS from at least 1/3 of severe storms that occur in my area. There is also line noise and distortion too that line interactive doesn’t protect against.
Ok so #1 I’m pretty blown away by 4 legit replies in sub 30min! This is my first time using L1’s forum. I know where the good people are now.
#2 Thank you all for sharing real world experience and insight and thanks Possum for the graphs. I feel comfortable now throwing one of my already owned line interactive UPS’s on for now. I will upgrade down the road a bit to full on double conversion but don’t feel under the gun to have to thrown down money right now.
Do you have Genmon setup? If you don’t, you may love it. All local monitoring and control of the generator. No internet required, all 100% self hosted.
Get yourself some eBay searched setup. I got my 3000VA Double Conversion unit for $700 new in box, which was a steal. It was missing the front bezel, but they stole one from another box and gave me it for free
Also, anything above 1500VA goes for cheap. The 2200VA and above units won’t plug into a 15a receptacle so they are less popular. But, there is nothing wrong with just not loading it above 15 or 20a depending on the circuit and swapping the plug
Or you could do what I did and run dedicated 30a circuits to power the UPS, etc.
What I did was run a 30a circuit to my server closet with my 3000VA double conversion unit, and then power inlets to my office, living room etc where all the PC’s are. Not every PC in my house gets the double conversion power. Super generator friendly and much cheaper than buying 4-5 UPS’s!
Possum you stole that 3000VA! I hadn’t considered buying a single larger unit and just setting up proper distro. I’m not too shabby of an electrician so wiring it up is no problem.
Dude that setup is on point! And no I’m unfamiliar with Genmon but am definitely going down that rabbit trail now. Thanks!
Keep your eyes peeled, I actually missed out on a dented SRT1500 for $150 no batteries, kicking myself I didn’t get it!
The centralized UPS has been something we love in our house. No big UPS under desks, no sizing UPS’s, no noise (Some UPS’s have a slight buzz/hum even when powered via mains) and everything plugged in will just work, forever
