| General > General Technical Chat |
| Noisy power from typical backup generators |
| << < (4/19) > >> |
| Renate:
Which subset of inverter generators are permanent magnet excited? I'm always amazed at how people size generators. They buy them without ever knowing what the load is. They run them without seeing how much power is being used. LED bulbs rock. I've had good luck with Aldi "Work Zone" products. YMMV |
| IDEngineer:
--- Quote from: Renate on February 24, 2021, 12:13:28 am ---They run them without seeing how much power is being used. --- End quote --- I'm just the opposite. I have one of those little plug-in-the-wall power monitors that displays voltage and frequency. I plug that in whenever the generator is running. Granted I'm only monitoring one of the two phases but the frequency has to be the same and the voltage is likely close. |
| bdunham7:
--- Quote from: IDEngineer on February 24, 2021, 12:17:24 am ---I'm just the opposite. I have one of those little plug-in-the-wall power monitors that displays voltage and frequency. I plug that in whenever the generator is running. Granted I'm only monitoring one of the two phases but the frequency has to be the same and the voltage is likely close. --- End quote --- If you are running a 120/240VAC portable non-inverter generator wired into your house, you can add phase imbalance to the list of things making your power quality poor. Also, most of those inverter generators are 120VAC only and the large plug you may see on many of them is just a 120VAC 30A 'RV' plug. The Champion one you listed is about the size they start being 120/240 split phase. |
| IDEngineer:
Agreed, I noticed that a while back. It's critical to confirm that the "big socket" on the panel lists 240VAC and not 120VAC. Our portable 2KW inverter only has traditional 120VAC sockets so no confusion. But you cannot run the house from it since it's only a single phase (in addition to being too small). Our existing big generator has both the 240VAC socket as well as an array of 120VAC's, the latter of which are split across the two phases so you can load them somewhat equally - which presumes the user is even thinking about that.... |
| james_s:
--- Quote from: IDEngineer on February 23, 2021, 09:38:23 pm ---I'm reluctant to parallel them because it halves your reliability. If either unit goes down, human intervention is required because anything on that phase - or any 240VAC loads across both phases - becomes inoperative. Meanwhile, things on the OTHER phase stay alive. That could play some weird games in your house. As just one (non-fatal) example, many 240VAC appliances run their electronic front ends on just one phase... not sure if their designers considered the proper action if the other phase drops. Or if the non-intelligent phase is alive while the intelligence isn't alive to control it. I'm also not sure what a "center-tapped" (so to speak) load were to only have one phase energized. Thus you're forced to scramble around to either kill the remaining generator, or rewire things so that the remaining generator attempts to power everything - in which case you're right back where you would have been with a single. This is why I've been watching the market for larger inverter-equipped units, and the Champion I mentioned fits that bill nicely: 7000 running watts in a single unit with clean power. Perhaps paralleled units are smart enough to disable themselves if the other unit dies. But in any case you're now dependent upon everything running properly on TWO engines. I'd rather have a single larger system. --- End quote --- They don't work like that. Parallel is just that, they're connected in parallel, the parallel cable sockets are internally just wired straight to the output receptacle. The way it works is whichever unit starts up first becomes the master and then when you start up the second unit it locks to the output of the master and comes on line, doubling the amount of current you can draw. If one fails or shuts down for some reason you drop back to the capacity of a single unit. The advantage is a significant fuel savings during times when only one is needed. The disadvantage is having two units to store and maintain, and that it's still only 120V, as far as I know none of the small inverter units produce split phase. You could use a transformer but what I do is just feed both sides of my transfer switch in parallel, there are no 240V loads wired to that anyway and if there were I don't expect having both sides floating 120V to ground with 0V between them would cause any problems. We don't have the shared neutral you sometimes see on kitchen circuits in Canada so that isn't an issue, and a 2kW generator is not going to overload a circuit anyway. It's an emergency backup generator so I can deal with some limitations, beats the pants off the candles and flashlights we used when I was a kid. |
| Navigation |
| Message Index |
| Next page |
| Previous page |