Reverse Site transformer to step upvoltage

[dave-the-diver]

I have a 110v generator.

I have a standard site transformer, 240v to 110v step down.

Can I connect the 110v output of my generator to the 110v sockets on my site transformer and get 240v out (from what would usually be the 240v in), or will I risk letting the smoke out?

David

[hidetheelephants]

You can, but it won't run very much; the typical 110 outlet(such as your generator) will be good for 16 amps, but at the other side of the transformer you get less than 8 amps at 240V. Fine for lighting or other light duties but no angle grinders or welding.

[Mr Pointy]

It will work but the killer issue (literally) is the the plug & sockets are all the wrong gender so you'll have voltage on exposed pins. To do it safely use a proper step-up transformer which has the right connectors:

https://www.screwfix.com/p/defender-3-3kva-intermi...

[hidetheelephants]

Indeed, it will kill you to death.

[mcflurry]

If you're starting with 220v, why step it down to 110v just to reverse it?
Can you not use the starting point power?

[dave-the-diver]

hidetheelephants said:

You can, but it won't run very much;

Nod, but 2kw genny has two 110v outlets, site transformer has 2 110v "inputs", so if I hook both up in parallel I should have 2kw 240v (less transformer losses), no?

Possibility of sparky death from exposed connectors recognised and understood.

David

[hidetheelephants]

Probably not, I'd be surprised if the outlets on the transformer aren't just 2 halfs of a common winding and connecting both to the same supply will cancel them out(and may cause the smoke to escape). You'll need to check with a meter to establish what's what.

[dave-the-diver]

Scared now.

What to check?

Look for any continuity between the pins of the two (originally) output sockets?

David

[Mr Pointy]

It's possible that the two 110V outputs are from different windings on the alternator so you can't just parrallel them together. For a general idea of how it might be wired:



Note this is just grabbed from a Google search so I'm not saying it's how your is wired but you can see the principle if you follow the cable colours. If you have a multimeter you could measure the N-N, N-L, L-N & L-L voltages on the 110v connectors& if you see 220v anywhere then they are different winding or phases, but it's unlikley to be a good idea to join both outlets. You can try it using one but you'll only get half the genny output power.

[OutInTheShed]

NO!

Aren't 110V site transformers normally centre tapped?
So they're really 55-0-55V

Does this mean you'll get 115V on the 'earth' of the 230 side? Or is it pot luck whether you get 'about zero' or 'about 230V' on the 'earth'?

Is the generator centre tapped and properly earthed?

[dave-the-diver]

Ah interesting.

Genny is a Honda EU2000.

Rated at 16VA continuous , 20VA Max

Nothing I can see says this is 20VA per outlet, so I guess there is no need (and possibly smokey) to use both, so will stick to 1 (probably lethal) male to male cable with 16A plugs (2.5mm2 flex) between the two.

Appreciate the thoughts.

David

[hidetheelephants]

The manual shows the outlets are common, so you could connect them to the same load but the continuous rating is only 16A anyway so it would likely overheat if you ask it to do that for very long.

[Mr Pointy]

Well, guess what, it looks like the outlets are just in parallel so there's no point in using both of them:



But the rest of the idea is still shonky.

[dave-the-diver]

hidetheelephants said:

it would likely overheat if you ask it to do that for very long.

Application is a pressure washer, so I've got a brilliant plan how to keep things cool.....

David

[OutInTheShed]

dave-the-diver said:

Ah interesting.

Genny is a Honda EU2000.

Rated at 16VA continuous , 20VA Max

Nothing I can see says this is 20VA per outlet, so I guess there is no need (and possibly smokey) to use both, so will stick to 1 (probably lethal) male to male cable with 16A plugs (2.5mm2 flex) between the two.

Appreciate the thoughts.

David

some Honda Inverter Generators are floating neutral, some are not?

[ferret50]

OP, Do you want roses or lilys on your coffin?

[netherfield]

ferret50 said:

OP, Do you want roses or lilys on your coffin?

Or are you doing a self cremation job?

[dave-the-diver]

netherfield said:

Or are you doing a self cremation job?

Unlikely. Whole kit and caboodle will be balanced on the roof of a boat so plenty of water around to douse any minor conflagration.
David

[Vanden Saab]

Just buy a 110v to 240v transformer. About £100.

[Rough101]

You have some good answers:

The genny alternator probably has 220v tappings, if so, just swap the outlets EDIT this is an inverter generator - that won’t work.

A site tranny is centre tapped to earth, so don’t run one backwards, even if you swap the outlet and inlet

You can buy a site step up tranny (blue box)

You won’t have much current available.

But I’d just buy a new one, unless it’s a Honda, they don’t last.

Edited by Rough101 on Wednesday 26th March 17:55