Two EU3000 (120V) generators, can I make 240 for some loads?

[wpns]

I've got two EU3000 generators that I can parallel to make 6KW (5.8 continuous) at 120Vac. This has worked fine when I could connect them both in parallel to both phases in my breaker box and only run 120V loads. But now I have HVAC splits and other 240V loads that I'd like to run, and I'd like to be able to use my existing generators.

I was hoping that the 'parallel' connections were some way of allowing the inverters to talk to each other and sync up their outputs, and that a low-power transformer would allow one of them to output a reversed phase, but it looks like they just sync up to each other over their output terminals.

Would something like: https://signaturesolar.com/growatt-5kw-split-phase-transformer-ats-5000t-es/ allow me to connect one generator L1-N and the other L2-N, produce 120/240 for the house, and have them pretty much share the load? [Assuming the load didn't exceed 5KW, and the imbalance didn't exceed 2.5KW, which I can manage manually].

I have a complex solar system without batteries, so (until I have batteries and some kind of hybrid system), this would just be for running the house with the solar disconnected.

Thanks!

 

[12VoltInstalls]

have a complex solar system without batteries, so (until I have batteries and some kind of hybrid system), this would just be for running the house with the solar disconnected

Look at the manufacturer for your generators and see if they offer a split phase parallel device. They probably don’t.

Plan B - I have a champion 6250 inverter generator. The CS call I made they said it isn’t split phase- just 120 or 240 only. But the wiring diagram shows two inverter outputs to feed L1 and L2 which also supply one 20A nema GFCI each with the same circuits and breakers. So that tells me it DOES offer discriminated 120+120 so other than any ‘imbalance’ issue I’m not aware of; since one can run one 120V outlet without concern and that circuit is the same as L1 (the second 120V outlet being the same wire as L2) that seems split phase capable.

I say all that because the 6250 open frame inverter generator from Champion- the largest inverter generator they make I believe- is economical to purchase (mine was <$600) and run, and will probably do your 240 loads.

I’d bet if a “parallel” split phase kit is offered it’s gonna be half the price of just buying a 240V generator.

 

[hwy17]

They cannot be paralleled to make split phase.

The transformer idea is possible, but I predict there will be GN bonding problems. Can the parallel combiner be unbonded? Probably not.

 

[12VoltInstalls]

They cannot be paralleled to make split phase.
The transformer idea is possible

The truth is almost biblical: basically EVERYTHING is possible; trying to do whatever is generally hardly ever practical LOL
“Everything is permissible, not everything is beneficial”

 

[wpns]

Can the parallel combiner be unbonded?

Don't see why not, it looks like the output is floating, I'll confirm with my DVM. Note that the anticipated use is not using the parallel combiner, but using the transformer to combine the two generators (and let the intrinsic parallel function keep them in sync).

 

[wpns]

Look at the manufacturer for your generators and see if they offer a split phase parallel device. They probably don’t.

Plan B - I have a champion 6250 inverter generator. The CS call I made they said it isn’t split phase- just 120 or 240 only. But the wiring diagram shows two inverter outputs to feed L1 and L2 which also supply one 20A nema GFCI each with the same circuits and breakers. So that tells me it DOES offer discriminated 120+120 so other than any ‘imbalance’ issue I’m not aware of; since one can run one 120V outlet without concern and that circuit is the same as L1 (the second 120V outlet being the same wire as L2) that seems split phase capable.

I say all that because the 6250 open frame inverter generator from Champion- the largest inverter generator they make I believe- is economical to purchase (mine was <$600) and run, and will probably do your 240 loads.

I’d bet if a “parallel” split phase kit is offered it’s gonna be half the price of just buying a 240V generator.

There's no manufacturer split-phase parallel device, unfortunately.

And yeah, the transformer above is 1/2 the cost of the indicated Champion generator, but then I'd have three generators to keep track of and maintain. I'm actually impressed with the Hondas, the sticker says I last fueled it up in 2018, and while it needed a new battery, it managed to start with the recoil starter! I'm going to do the full maintenance schedule, but Not Today. 8*)

 

[hwy17]

Oh wait that transformer is 240v single phase to split so it won't work.

You would need a 120v single to 120/240 split phase transformer.

You cannot get 240v out of two 120v generators. You just can't.

 

[wpns]

transformer is 240v single phase to split so it won't work

Aren't transformers bidirectional? It _looks_ like it's a single winding, but if it's not, can't I just use the split winding?

 

[hwy17]

Aren't transformers bidirectional? It _looks_ like it's a single winding, but if it's not, can't I just use the split winding?

You could but then you would get 240v single phase out the other end, not split phase.

With two of the transformers you could theoretically go 120 to 240 and then 240 to 120/240.

 

[wpns]

You could but then you would get 240v single phase out the other end, not split phase.

With two of the transformers you could theoretically go 120 to 240 and then 240 to 120/240.

Why not just use the one split winding in the transformer and leave the other winding (if there is one) unconnected? Won't that do the autotransformer thing?

 

[12VoltInstalls]

then I'd have three generators to keep track of and maintain a generator to sell and offset the cost of a new one

Fixed it for you

 

[hwy17]

Why not just use the one split winding in the transformer and leave the other winding (if there is one) unconnected? Won't that do the autotransformer thing?

I thought only auto transformers could do that but you could be right.

 

[marionw]

There are autotransformers that convert the 120vac input to split phase 240vac output.

Might be what you are looking for.

Victron-Energy-Autotransformer

Growatt AutoTransformer