three phase from 240v.....

[Gareth J]

Back to solar

SolarEdge make domestic sized 3 phase inverters, that simply switch off if there is no load. They are also releasing a smaller inverter with a built in battery, currently only 60kw I think

Yes, there are plenty of smallish 3phase inverter offerings. However, any that fit the OP's bill in one hit?

I.e; must be able to generate 3phase with only a single phase grid.

I don't know enough about what's available, or not, to know for sure, but I suspect that to achieve what he'd like to, he'd need two inverters, connected via a battery bank. One hybrid single phase one for the grid tied single phase + PV +batteries side and a 3phase, islanded inverter for the workshop 3phase, fed by the batteries. Can all this be achieves with a single, very clever, inverter?

 

[Kayos]

Yes, there are plenty of smallish 3phase inverter offerings. However, any that fit the OP's bill in one hit?

I.e; must be able to generate 3phase with only a single phase grid.

I don't know enough about what's available, or not, to know for sure, but I suspect that to achieve what he'd like to, he'd need two inverters, connected via a battery bank. One hybrid single phase one for the grid tied single phase + PV +batteries side and a 3phase, islanded inverter for the workshop 3phase, fed by the batteries. Can all this be achieves with a single, very clever, inverter?

Plenty of setups do not need any grid connection to work, to achieve the 3 phase could all indeed be done with 1 inverter, however it will not be cheap

We are installing 3MW of private wire currently that does not have any grid tie, we looked at sleeving to another site but full self consumption is assured

 

[Gareth J]

Plenty of setups do not need any grid connection to work, to achieve the 3 phase could all indeed be done with 1 inverter, however it will not be cheap

We are installing 3MW of private wire currently that does not have any grid tie, we looked at sleeving to another site but full self consumption is assured

Of course islanded 3phase setups exist. And not necessarily *that* expensive a ones either. However, specifically, the OP would need to connect the single phase grid, solar panels, batteries and have the option of 3phase out. I don't know if there is a single inverter available that can achieve this. Do you? Please let me know if you do - it'd be very useful and definitely might be a thing

 

[Onoff]

I'm building an 8HP rotary one. Work in progress.

https://flic.kr/p/2mFZr3y

 

[knighty]

I'm surprised no-one runs

I'm building an 8HP rotary one. Work in progress.

https://flic.kr/p/2mFZr3y

why 2 motors? just what you had handy vs one big one?
1
also, I'm assuming using the 110 transformer backwards to step mains up to the 400v range... motors are wired in star, I'd have thought with that setup you'd connect the mains negative to the star point of the 3 phase motors?

 

[m_c]

I'm surprised no-one runs


why 2 motors? just what you had handy vs one big one?
1
also, I'm assuming using the 110 transformer backwards to step mains up to the 400v range... motors are wired in star, I'd have thought with that setup you'd connect the mains negative to the star point of the 3 phase motors?

For a standard 3P setup, there is no need to have the motor star point connected to anything.
It's only if you need 3P+N, that you would need it connected.

What people quite often don't understand, is two legs are essentially single phase.
240V mains is essentially a centre tapped 415V supply, just the same way as 110V is centre tapped to give two 55V feeds in relation to neutral/centre tap.

From a technical point, if you connect it to the incoming neutral, then you bypass isolation (that's assuming the transformer is isolated, and not auto-wound - if it's autowound it would result in creating a short circuit).
Depending on the final three phase setup you'd like, technically you could connect the star point to ground, which would give you the equivalent of mains 3 phase, where neutral is connected to ground (I'm sure one of the resident sparks will give the correct technical name for it..).

 

[Onoff]

I'm surprised no-one runs


why 2 motors? just what you had handy vs one big one?
1
also, I'm assuming using the 110 transformer backwards to step mains up to the 400v range... motors are wired in star, I'd have thought with that setup you'd connect the mains negative to the star point of the 3 phase motors?

Two near identical motors as that's all that I could lay my hands on.

The big 5kVA trannie is rewired as an autotransformer to give out nom 230+110.

A mate from another forum made the board with all the capacitors on and successfully used it until he got proper three phase laid on.

Have a read here:

Rotary Converter

A mate off another forum made and gave me this. Uses a 110V transformer re-jigged as an auto transformer to give nom 340V (230+110). He used it for ages with a 7.5HP motor and said it ran everything just fine in his shop until he got proper 3 phase. Wire missing in the photo goes from the bfo...

www.mig-welding.co.uk

I also acquired 4 Chinesium V/A/Hz meters.

The green will be for the incoming 230V mains. The RYB for the 3 phase output.

If the converter works, I'll case it up and make a pretty bezel for meters. At the mo just on a 3D printed bracket I can hook somewhere as I play with the wiring.

 

[Gareth J]

Two near identical motors as that's all that I could lay my hands on.

The big 5kVA trannie is rewired as an autotransformer to give out nom 230+110.

A mate from another forum made the board with all the capacitors on and successfully used it until he got proper three phase laid on.

Have a read here:

Rotary Converter

A mate off another forum made and gave me this. Uses a 110V transformer re-jigged as an auto transformer to give nom 340V (230+110). He used it for ages with a 7.5HP motor and said it ran everything just fine in his shop until he got proper 3 phase. Wire missing in the photo goes from the bfo...

www.mig-welding.co.uk

I also acquired 4 Chinesium V/A/Hz meters.

View attachment 380938

View attachment 380937

The green will be for the incoming 230V mains. The RYB for the 3 phase output.

If the converter works, I'll case it up and make a pretty bezel for meters. At the mo just on a 3D printed bracket I can hook somewhere as I play with the wiring.

That's a neat idea with the meters. I've a "415"V static one and probing the different phases during start/run and different load situations was interesting.

 

[Onoff]

That's a neat idea with the meters. I've a "415"V static one and probing the different phases during start/run and different load situations was interesting.

I got the 3 in 1 Geekcreit meters that included frequency readout with square bezels. Paid about a fiver each on Banggood. Can't seem to find them again but there's these, with just volts and amps only plus dirt cheap:

[£2.75 50% OFF]Geekcreit® 2in1 22mm AC50-500V 0-100A Amp Voltmeter Ammeter Voltage Current Meter With CT Au23 Electronic Accessories & Supplies from Electronic Components & Supplies on banggood

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banggood.onelink.me

 

[Seadog]

They're about half the price of the ones that I bought three years ago

 

[Onoff]

They're about half the price of the ones that I bought three years ago

Same here. My square ones are fine for what I'm using them for but there was certainly one led segment duff in at least one. I don't think I ever powerered them all up. Worst case 70A might show as 10A!