110v at the generator or the other end of the 175 feet of 10 AWG wire?
And total load is 5-6 amps each including the UPS charging the batteries? What kind of UPS? Something like an APC will have a relatively low charging current, other setups may be quite a bit higher. I know our Alpha UPS units have programmable charging current and I had to lower it in case the only generator I have available is our smallest Honda 1000 VA, otherwise the generator would run for a minute or two and then trip on overload. Doing the math on voltage drop in the wire, 10 AWG is around 1 ohm per 1000 feet, and you have 350 feet of wire including hot and neutral. So 0.35 ohm times 5.5 amps is 2 volts. Assuming the generator is putting out 120 volts, that wouldn’t account for a 10 volt drop. Sounds like you suspect the generator can’t handle the load and as a result is putting out low voltage. What kind of generator is this? Is it an inverter style? What is the VA rating? If it’s just a standard generator for power tools and stuff, a UPS will sometimes find the voltage or frequency out of spec or unstable and refuse to run off it. If it’s just an APC UPS or something like that, sometimes they have a sensitivity setting that you can set lower. From: AF <af-boun...@af.afmug.com> On Behalf Of Josh Luthman Sent: Monday, September 21, 2020 9:22 AM To: AFMUG <af@af.afmug.com> Subject: [AFMUG] Generator power supply questions So Friday we have another 3 phase go down in the building. They unplugged it all so that wing had nothing. As a precaution I start up the generator. When they're cutting the other phases we are using I move it to the generator. The generator complains and the UPS units don't switch over. I drop it to say 90% open choke and the UPS switches over - but it's only 110v. I'd like to know what's going on here. I have 175 feet of 10 gauge (times 2). Two circuits on the generator, two runs of copper, two UPS. UPS is doing about 5-6 amps each. What can I do better? Should I? It runs but I'd like to keep it as simple as possible to avoid "teaching someone" to lower it from full open choke. Josh Luthman 24/7 Help Desk: 937-552-2340 Direct: 937-552-2343 1100 Wayne St Suite 1337 Troy, OH 45373
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