VFDs. Again

James1979 · Jun 30, 2021

Thought id start a new thread rather than jam up someone else’s.

I have a mill, saw and hoist which are 3ph from old workshop. They are too good to sell but currently unused. I was hoping to find another workshop in the near future but that isn’t happening as quick as I wanted so does the collective think any of these would run off a vfd from 240 1ph please?

More photos if required but access is the issue on the saw (last pic). I haven’t taken the hoist apart (2nd pic) to get at the motor but can do if required. Hoping that at least would work as it’s handy.

Kram · Jun 30, 2021

They all look like 440v in delta, so you'd want a boost vfd to run them properly, which are quite a bit more expensive.

However a mill, saw and hoist, tools where running speed might not be too important most of the time. 3ph motors have a volts * frequency curve and 240v will be about 25hz, so half speed if you can live with that.

James1979 · Jun 30, 2021

Ok thanks. That’s appreciated. So they will run with a 240-415 vfd?
I can live with half speed on the hoist and bandsaw. all the saw motor does is run a v belt to a pump so I can adjust the pulleys to compensate.

The hoist isn’t that meaty just a few hundred kg. It’s more useful as a second pair of hands than anything so speed isn’t that critical. May even put it on a trolley for loading the plasma table.

James1979 · Jun 30, 2021

I have seen this

4kW Single-phase VFD Inverter Frequency Converter 220V to 3-phase 400Hz output | eBay

<body>4kW Single-phase VFD Inverter Frequency Converter 220V to 3-phase 400Hz output. Used but in good working order. Michael 07508704811</body>

www.ebay.co.uk

Asked him for more info so I can get a manual and see what’s what.

Jan-DIY · Jun 30, 2021

If your motor needs already 400 in delta it needs lot more in star connection.
If it is about 400 in star than you can get them to 230 in delta.

You need to have a look at VFD which deliver 400V on Output.

julianf · Jun 30, 2021

I've been looking at boost units and they're a lot cheaper than I thought.

I can't work out the kw of your unit - it seems confusingly low from the plates that I'm seeing?

As an example, a 380v 0.75 KW boost is well under £100 off Ali express.

James1979 · Jun 30, 2021

It does seem low but it’s not a big motor. I suppose it’s not driving a massive amount on a mill?

if that’s the case then I’ll be happy. Much cheaper and easier than I thought.

julianf · Jun 30, 2021

James1979 said:
It does seem low but it’s not a big motor. I suppose it’s not driving a massive amount on a mill?

if that’s the case then I’ll be happy. Much cheaper and easier than I thought.

I've acquired that wadkin planer thicknesser - I wanted one for years, but so many forum posts about how they were difficult or expensive to run on 1ph, but (not that I've done it yet) it all seems way cheaper and easier than I was lead to believe.

If you find my recent thread on it, there's a post on the bottom of, I think, the first page, with a link to Ali express selling boost converters. Stangely they're all the same part from the same seller (I think) but the price for the same spec of unit varies between the different listings, so have a look at a few, rather than just clicking on the first one.

Kram · Jun 30, 2021

James1979 said:
I have seen this

4kW Single-phase VFD Inverter Frequency Converter 220V to 3-phase 400Hz output | eBay

<body>4kW Single-phase VFD Inverter Frequency Converter 220V to 3-phase 400Hz output. Used but in good working order. Michael 07508704811</body>

www.ebay.co.uk

Asked him for more info so I can get a manual and see what’s what.

Dont buy that, first it looks to be a standard 240v verion, not a 400v output but 400hz which is common to all vfd's , which means a suitable motor will run upto 8x the 50hz mains speed - normal 50hz motor probably explode if you try it, upto 75-100hz is generally safe maximum.

Amazon recently had similar models new for under 30, and they will again soon enough. Current price is under 100, with the boost ones a bit more.

1.5kw boost £107
www.amazon.co.uk/Variable-Frequency-Drive%EF%BC%8C1-Phase-Inverter-Controller/dp/B07X11HTXZ/

5.5kw boost £132
www.amazon.co.uk/Inverter-Frequency-Converter-Single-Phase-controller/dp/B089W81GC8/

julianf · Jun 30, 2021

If the unit really is as low a wattage as implied, then a cheaper option (on the same part) can be found here -

Page Not Found - Aliexpress.com

Im unsure how aliexpress is currently dealing with VAT - they should collect it on checkout, so the price you see *should* be your final price, but who knows.

Jan-DIY · Jun 30, 2021

First picture motor rated with 7amps.
So you need the bigger one.
One additional thing.
As in general VFD are connected straight to its motor it can get complicated for driving your hoist because I believe it got a separate control.
Don’t know about OC behavior on this VFD but for sure Danfoss devices will show you a warning.

m_c · Jun 30, 2021

James1979 said:
I have seen this

4kW Single-phase VFD Inverter Frequency Converter 220V to 3-phase 400Hz output | eBay

<body>4kW Single-phase VFD Inverter Frequency Converter 220V to 3-phase 400Hz output. Used but in good working order. Michael 07508704811</body>

www.ebay.co.uk

Asked him for more info so I can get a manual and see what’s what.

That's just a 240V 4KW HY inverter.

Kram said:
They all look like 440v in delta, so you'd want a boost vfd to run them properly, which are quite a bit more expensive.

However a mill, saw and hoist, tools where running speed might not be too important most of the time. 3ph motors have a volts * frequency curve and 240v will be about 25hz, so half speed if you can live with that.

29Hz is the magic number - HowTo: 240V Supply to a 400V AC Motor - Application Detail (inverterdrive.com)
You have to remember that induction motors are essentially a constant torque source, so using that setup, you'll only get around 60% of maximum power, and potentially have cooling issues due to the lower speed.

James1979 · Jun 30, 2021

Thanks gents. Those ones on Ali express look useable for what I want. The hoist may just have to get sold. I can always buy a 240v or even better an air one.

I’d be happy with the mill running. Very happy in fact

Kram · Jun 30, 2021

m_c said:
cooling issues due to the lower speed.

Mines a slow 6 pole, should be worse effected by slow speed, maybe they put a better fan as it doesnt even get warm - long after the vfd fan has been running a while. Ive got the thermistor trip wired up it has never tripped.

m_c · Jun 30, 2021

Kram said:
Mines a slow 6 pole, should be worse effected by slow speed, maybe they put a better fan as it doesnt even get warm - long after the vfd fan has been running a while. Ive got the thermistor trip wired up it has never tripped.

For the majority of uses, cooling shouldn't be an issue, but it's something to be aware off if you're planning on using maximum power available at low speeds.

Smouser · Jul 9, 2021

James1979 said:
Thought id start a new thread rather than jam up someone else’s.

I have a mill, saw and hoist which are 3ph from old workshop. They are too good to sell but currently unused. I was hoping to find another workshop in the near future but that isn’t happening as quick as I wanted so does the collective think any of these would run off a vfd from 240 1ph please?

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More photos if required but access is the issue on the saw (last pic). I haven’t taken the hoist apart (2nd pic) to get at the motor but can do if required. Hoping that at least would work as it’s handy.

You could try to rewire the motors so they can be wired in Delta yourself?

I managed to do a motor earlier this year and it works a treat.

Rewiring a 3 phase motor to Delta

I recently got a three phase motor with a machine that is 950RPM (uncommon) but unfortunately it is only wired for 380/440v (background https://www.ukworkshop.co.uk/threads/rewiring-a-3-phase-motor-to-delta.130053/). I am looking to rewire the motor so that I can use a VFD @ ~240v. Would...

www.mig-welding.co.uk

*Edit*
I see the first motor is already wired in Delta so no luck with that one. Maybe the other two?

VFDs. Again

James1979

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Kram

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James1979

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James1979

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4kW Single-phase VFD Inverter Frequency Converter 220V to 3-phase 400Hz output | eBay

Jan-DIY

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julianf

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julianf

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Kram

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4kW Single-phase VFD Inverter Frequency Converter 220V to 3-phase 400Hz output | eBay

julianf

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Jan-DIY

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m_c

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4kW Single-phase VFD Inverter Frequency Converter 220V to 3-phase 400Hz output | eBay

James1979

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Kram

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m_c

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Smouser

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Rewiring a 3 phase motor to Delta