Electronics > Projects, Designs, and Technical Stuff
Any motor/generator guys on here? - Project Complete - Thank You
JayArr:
Hi All
My latest project is a generator. I bought it used on Craigslist and it worked perfectly - no problems at all. It is listed as 4000W but that's peak and it is 3600W running.
It came wound as two 120VAC 15A circuits in series and also provided a 240VAC 15A socket.
What I need for my travel trailer is 120VAC at 30A. I figured it would be easy to swap the stator windings from series to parallel to get my 30A.
The universe, however, decided to complicate things....
When I pulled the end off I found five pigtails (I expected three). It seems there are four sets of windings, each 120V leg has two sets of windings and the center tap of those windings is what is connected to the AVR for voltage detect.
On top of that the windings aren't in the configuration I've seen schematics of or that I expect.
Take a look at my schematic and tell me if you understand what they did here.
wizard69:
I know a little bit about AC motors but this generator has me puzzled.
--- Quote from: JayArr on May 03, 2021, 07:46:31 pm ---Hi All
My latest project is a generator. I bought it used on Craigslist and it worked perfectly - no problems at all. It is listed as 4000W but that's peak and it is 3600W running.
It came wound as two 120VAC 15A circuits in series and also provided a 240VAC 15A socket.
--- End quote ---
So 3 sockets? Also if I understand your description correctly you already have 30 amps of 120VAC power, it is just split across two "Phases". It isn't clear as to how the 120 outlets are wired up.
I suppose you could run the 240 AC into a transformer as another way to get to 30 amps.
--- Quote ---
What I need for my travel trailer is 120VAC at 30A. I figured it would be easy to swap the stator windings from series to parallel to get my 30A.
--- End quote ---
30 Amps is a lot for a travel trailer, are you sure that it needs that much power to be functional? If there is a big load, say an air conditioner, I'd seriously consider simply putting it on a separate circuit.
The reason I ask is that 30 amp outlets are fairly common at RV parks, it doesn't actually imply what a trailer will actually burden the connection with. Another thing worth considering if the trailer is old would be to migrate to more efficient electrical appliances.
--- Quote ---
The universe, however, decided to complicate things....
When I pulled the end off I found five pigtails (I expected three). It seems there are four sets of windings, each 120V leg has two sets of windings and the center tap of those windings is what is connected to the AVR for voltage detect.
On top of that the windings aren't in the configuration I've seen schematics of or that I expect.
Take a look at my schematic and tell me if you understand what they did here.
--- End quote ---
I'm not sure what is up. It could be a case of a gen set that is designed to support a wide array of markets. You might want to search for a technical manual if you can find the actual manufacture of the generator.
You may also want to watch out for other potential issues such as a controller that only understands the current connection method and the possibility that the engine might not be able to drive the generator properly if the load changes dramatically. This leads me back to being inclined to leave the gen set alone and solve the power problems in another manner. If the gen set has to be replaced in the future you may find yourself going through another modification event. For me it is better to see the gen set as a module that is easily swapped with another power source as needed.
JayArr:
Thanks for the reply Wizard
Yes, correct, two out of phase 120VAC windings that have been joined in series to make 240VAC available.
My Xantrex battery charger pulls 22Amps at full throttle so a 30A source is required.
I've thought of a transformer but a decent (non-Chinese) 5000W transformer is 89 pounds and $1000. That's not a solution I can afford.
I've already bought and paid for this genset, I've also bought a new carb, a propane conversion kit, new rubber mounts and a K&N air filter so it would be really hard to walk away from.
It's just wiring, I'm sure it can be done I just have to keep asking until I find someone who knows how.
tpowell1830:
There are different configurations of generators, depending on brand, output, etc. You did not mention the brand of your genset.
This YT guy repairs generators and seems to know how to repair them very well, maybe he has a video that fits your needs. I am subscribed to his channel and watch his videos frequently.
https://www.youtube.com/channel/UCr_GXW2Y56hOpGchXYNqZOQ
james_s:
Usually the problem is going the other direction, most inverter generators have the 30A 120V socket but can't do 240V which is ideal for powering a house. You could always sell that generator now that you've got it in good working order and put the money toward an inverter generator which will be much nicer to your fellow campers, unless you're off in the middle of nowhere with nobody else around. Those 3600 RPM generators are obnoxiously loud, having gone to an inverter generator I'd never go back. The windings must be 180 degrees out of phase though in order to get 240V so it should be possible to wire them in parallel.
Can your charger accept 240V? That might be another option, run that on 240 at which point the current is half. Whether that is feasible depends on what other 120V loads are in the camper and how they're wired.
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