three phase converters

[Hardwicke]

What sort of converter do I need for a 220-240v 25hp motor? The plaque states ;
A1W2 41161W 20 polyphase 50~ 220-240v 25hp 1/.56A 2850 rpm

IMG20230804125726.jpg

[Noel]

A converter to do what? If I read the data plate correctly [and I am not an electrician] what you have is an AC motor designed to work on 50 cycles/second 3 phase supply, at UK mains voltage or somewhat above. I suggest that you need to consult an electrician familiar with industrial AC motors.

[James Walters]

The plate reads 1/4 hp. (.25)
25hp would be a very big motor indeed

[Hardwicke]

It's a milling machine

[Hardwicke]

The plate reads 1/4 hp. (.25)
25hp would be a very big motor indeed

Thank you. Now I can see the decimal point !

[Hardwicke]

Found these online but still concerned if I've got the amps right.

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[davebradwell]

I suggest your cheapest option may well be to dump the motor and find a used single phase job. I use a converter for a range of machines but there's not much point for just one and if you don't use the correct converter settings, some motors get very hot. Alternative is to use an inverter and benefit from variable speed.

DaveB

[Martin Wynne]

Hi,

An inverter/phase converter will cost more than a new motor.

Here is a single-phase 1/4HP motor with free next-day delivery:

https://www.mmengservices.co.uk/collect ... -3000rpm-1

p.s. this type of motor won't start under load, but if it's for a milling machine you won't be doing that.

Or pay a bit more for a bigger 1/2HP capacitor-start motor which will start under load:

https://www.mmengservices.co.uk/collect ... le-3000rpm

(Not recommendations, just a Google search -- old date on web site so phone first)

Martin.

[Hardwicke]

Thanks Dave and Martin. When I bought it the seller suggested swapping the motor as an option. The price for the converter is about the same as a motor. I've a grinding wheel too but I'll have to check the motor spec. Everything else I have is normal single phase. It's not an essential buy just at the moment but I'd like to get it working.

[Paul Townsend]

Generally 3Ph motor will run more smoothly than 1Ph so definite benefit for a mill or lathe...better finish results if you can afford the converter.

[sebring115]

You need an invertor. The great thing is that it will give you infinitely variable speed control so is much better than a single phase motor, no need to change gear or mess with belts. I like Mitsubishi frequol ones. Someone like newton tesla will be able to help you. https://www.newton-tesla.co.uk/

Something like this would work, but always check it’s single phase input which I think this is. https://www.ebay.co.uk/itm/134189715421 ... edia=EMAIL

[James Walters]

I converted my Colchester Lathe and Harrison milling machines to run using inverters (VFD's), despite at the time having a 3 phase supply available.
The conversions were simple and the benefits many. Soft-start/stop, jog, fwd/rev, variable speed, etc. It is also very easy to add additional safety cut-outs should they be required.
I rarely need to change speeds via the gearbox anymore, and enjoy the luxury of being able to adjust speeds on the fly with the cutter engaged to tweak the perfect cut.
I would recommend visiting the drives direct website. There is lots of useful information on there, and they were very helpful to me on the phone when I was first looking to do what you are planning.

http://www.drivesdirect.co.uk/