Converting 3ph generator to 1ph

Bruthal

For a 3 phase and N socket, it would be star output.

funkey_monkey

I've been told there is something that can be done by modifying one of the phases to tap one off with an earth.
Not quite sure what it means yet so still trying to figure it out.

air

funkey_monkey wrote: »

I've been told there is something that can be done by modifying one of the phases to tap one off with an earth.
Not quite sure what it means yet so still trying to figure it out.

There isn't, that's what you have already as Bruthal has pointed out.
Each of the 3 single phase sockets is likely connected to a point on the star.
The star centre point forms your neutral (and earth) connection if you install an earth rod when running it.

Without modification or additional equipment your only option is to use single phase loads under the power rating of each phase, I'd suggest no more than 1.5kW.

air

Bruthal wrote: »

It should. But generators dont run as smoothly with 1 phase fully loaded and the other 2 with nothing.

I think it may depend to some extent on the number of poles on the generator head and how they are distributed.
It can be possible to have a pretty balanced (mechanical) load with only a single phase so long as there is nothing at all on the other two in some cases.

I've certainly seen it done and one quite large set I know of has ran like that for many years without issue.

On a small set like this I wouldn't be too optimistic of smooth running!

funkey_monkey

air wrote: »

Without modification or additional equipment your only option is to use single phase loads under the power rating of each phase, I'd suggest no more than 1.5kW.

This is what I was initially asking. What do I need in order to do this fully and correctly.

The method I was told about was phase-netural which you state above, but only having 1.5kW may not be sufficient for a kettle or some tools under load.

funkey_monkey

Can I sue something like this (maybe a better quality one, but similar nonetheless:

https://www.ebay.co.uk/itm/GENERATOR-SINGLE-PHASE-4-7-KW-AVR-VOLTAGE-REGULATOR/313038574076?hash=item48e28d91fc:g:oIgAAOSwLSZcFQy7

funkey_monkey

Just checked the AVR on the generator and the it is rated as 2.5kW.
So, as I told the owner initially I didn't think it was a 6kW generator. Or do the phases come into play here?

Would this be more than likely a 2kW generator and should it be expected to boil a kettle rated at 2.2kW?

air

It's just the rating per phase.
As I alluded to earlier, the AVR can only control the rotor current based on the voltage on a single phase (or the lowest voltage across all 3 hopefully).
Changing to a single phase avr won't help you at all. I'd imagine the only difference is that it only has a single voltage input.

The issue you have is that the generator head has 3 sets of windings instead of a single one (in simple terms).
The output of each of your 3 windings is unfortunately (for your purposes) 120 degrees out of phase so you can't simply parallel their outputs (this would short them out effectively).

Like I said, the best practical options in order of preference are:

1. Sell and buy a single phase unit
2. Make do with 1.5kW output
3. Find a single phase generator head and avr for it and swap that out.
4 . Rectify and invert the output as has been suggested

Option 1 really is the winner in my opinion.
A 3 phase set with that kind of power rating is going to have quite a limited market unfortunately as it's of limited use as you have discovered.

2011

I worked with a company (sadly no more) where we had exactly this issue. A 3 phase supply but we needed single phase. We also needed to balance the loading across the 3 phases as evenly as possible. One solution we explored was a “Scott-T” transformer. They are quite unusual but will do the trick.

As transformers are passive units there is very little to go wrong with them.

funkey_monkey

2011 wrote: »

I worked with a company (sadly no more) where we had exactly this issue. A 3 phase supply but we needed single phase. We also needed to balance the loading across the 3 phases as evenly as possible. One solution we explored was a “Scott-T” transformer. They are quite unusual but will do the trick.

As transformers are passive units there is very little to go wrong with them.

Rectify and invert the output as has been suggested

Any ideas if/where I could source a product (or even a price) for the transformer or a rectifier/inverter?
TBH - I'm not sure what I'd been looking for and the owner is asking me if I've found out what to do yet.

funkey_monkey

Penny might have dropped here. On front there are three 220v outlets and a 380v outlet of larger diameter.
Is the large outlet 3 phase and the 3 smaller ones an output for each phase?

2011

funkey_monkey wrote: »

Any ideas if/where I could source a product (or even a price) for the transformer or a rectifier/inverter?
TBH - I'm not sure what I'd been looking for and the owner is asking me if I've found out what to do yet.

That is the beauty of the Scott T transformer solution, simplicity. You don't need a rectifier, all you need is a transformer. I think you may have to get it specially made. From memory our 3 kVA unit cost around €400 and we got it made in Ireland.

Tuco88

I would be in the same camp as selling at at this stage.How often will it be needed?


You could install a VIP meter on the unit, anything that will tell you the amps/voltage per phase. So at least you can balance the loads over the 3 single phase outlets as best as you can.

funkey_monkey

So two of the single phases cannot be linked to provide increased current and there fore power?

funkey_monkey

Tuco88 wrote: »

I would be in the same camp as selling at at this stage.How often will it be needed?


You could install a VIP meter on the unit, anything that will tell you the amps/voltage per phase. So at least you can balance the loads over the 3 single phase outlets as best as you can.

It will be used regularly as in daily in the shed especially over winter, maybe less so in the summer months.

air

funkey_monkey wrote: »

Penny might have dropped here. On front there are three 220v outlets and a 380v outlet of larger diameter.
Is the large outlet 3 phase and the 3 smaller ones an output for each phase?

Yes, almost certainly.

funkey_monkey

Can one of these inverters be used on the Generators 12V DC/8.3A output?

It has a continuous power rating of 2kW and 4kW peak.

Yinleader 2000W (4000W Peak) POWER INVERTER DC TO AC 12V TO 230V 240V WITH SOFT START

air

funkey_monkey wrote: »

It has a continuous power rating of 2kW and 4kW peak.

It does, but to provide 2kW it needs a 12V supply source capable of providing about 200A - a bit more than the 8.3A the 12V winding on your head can provide!

That 12V output is designed for keeping starter batteries topped up and no more.

Bruthal

Yea the 12v output is about 0.1kw.

funkey_monkey

Owner now wants to know what would happen if he put a 3 plug on the end of the 3 phase outlet?
Would that be any different to his single phase outlets?
My understanding is that 3 phase has 3 hot wires - one for each phase and a neutral. There is also an earth. So he can't get anything better than what the single phase outlets provide him.
Correct?

Bruthal

funkey_monkey wrote: »

Owner now wants to know what would happen if he put a 3 plug on the end of the 3 phase outlet?
Would that be any different to his single phase outlets?
My understanding is that 3 phase has 3 hot wires - one for each phase and a neutral. There is also an earth. So he can't get anything better than what the single phase outlets provide him.
Correct?

Yes the 3 phase outlet is just 3 phases and N.

What is the precise use he wants to use the generator for?

Edit: O yes shed, and house backup.

funkey_monkey

Bruthal wrote: »

Yes the 3 phase outlet is just 3 phases and N.

What is the precise use he wants to use the generator for?

Edit: O yes shed, and house backup.

I don't think he believes me - either that or he is trying to get out of a hole. Two of them bought.

Bruthal

Well the 3 phases are not simply 3 phase wires of course. But in terms of running things like a kettle, it doesnt change anything from before.

It would be interesting to see will it boil the kettle if you added heaters to the other 2 single phase sockets

funkey_monkey

Bruthal wrote: »

It would be interesting to see will it boil the kettle if you added heaters to the other 2 single phase sockets

Why would that make a difference. - something to do with load balancing?

autumnalcore

Thread has gone from 'what's the best way of doing this properly' to if I throw away 4kw of power (probably 10kw of petrol) can I boil a kettle.

The fella bought the wrong thing for the job, no good will come of your trying to fit a square peg in around hole.

Even if you break your back cutting the proverbial corners off the peg and beating it into the hole with a sledgehammer you'll still have no thanks from fella that 'doesnt believe you' and when the Chinese ****e blows up down the line which I can 100% guarantee it will you'll have a big target painted on your ass.

Bruthal

Feck it in anyway, no boiling the kettle so.

I'm sure there were kettles before electricity.

foxy farmer

What size engine is driving the alternator?

funkey_monkey

6.5hp.

I've suggested his shed is changed over to led lights which will get rid of halogen floodlights that are currently in place and also swap old the old bulbs too. That should reduce the burden on the generator.

If he desperately needs a kettle I've told him to put in a gas hob or get a caravaners kettle which is only 1kW.