3 phase run off 240 single phase?

[BrokenBiker]

Suds pump on my lathe is still 3 phase, but was wired up along with the lathe when I collected, although I will admit I didn't try it to see if it worked.

I've cleaned it up and now noticed the motor plate says 3 phase 400v...

Can it be wired to run at all off 240v single phase relatively easilly?

I plan on making a small control box for the lathe to house main switch, contactor, e-stop and a switch for suds pump at some point, and eventually a reverse switch as I've found access to the motor that will let me get in there now. Would rather get everything up and running properly before tidying it all up I to 1 box though so if it can't be wired to run on 240 I will have to look at other options, or get a VFD for it (annoyingly I bought one for the lathe, then when i realised it was single phase I sold the VFD)

 

[brightspark]

wont even run of an 240v to 3 phase inverter as its only 400v motor not dual voltage

 

[Seadog]

It will run, but at reduced speed.

 

[julianf]

https://www.amazon.co.uk/dp/B07X11HTXZ?th=1

I have one, but mine was £50 on one of @Kram 's amazon spots, IIRC.

May be simpler just to fit another pump?

 

[Memmeddu]

wont even run of an 240v to 3 phase inverter as its only 400v motor not dual voltage

Most likely

It will run, but at reduced speed.

May work but not for long

What really matters on Induction motors is frequency and number of fields in the stator windings.
Now at lower voltage equals more current
If not wired properly it will probably still be able to run maybe once helped to spin, but 99% sure it will over heat and burn.
Now coolant pumps on machinery are 90% of the times dual voltage so if you go to inspect the junction box on the motor you may most likely find a diagram for Delta or star wiring upon input voltage
But that's the only way a perfect nobody can understand if a three phase motor can be run on 220V.
An electric guy (sounds a lot strange I know) could even open the housings and redo the single connections on the stator windings to make the motor capable of doing so

 

[BrokenBiker]

new pump it is then

 

[6ply]

It will run, but at reduced speed.

My understanding is that speed of the motor is determined by the frequency and not the voltage. With reduced voltage there would be less power but it should still run.

 

[6ply]

new pump it is then

Don't give up just yet. I have rewired several suds pumps and as far as I recall most of them allow rewiring in delta or Star configuration even though this might not be explicitly stated on the data plate. Take the connection plate off and have a look at the terminal connections inside. There may even be a diagram indicating how it should be wired.

Also bear in mind that small suds pump motors can often be run from single phase supplies just with the addition of a capacitor.

 

[ajlelectronics]

My understanding is that speed of the motor is determined by the frequency and not the voltage. With reduced voltage there would be less power but it should still run.

If it is a synchronous motor. That is how electric clocks kept their time.

 

[BrokenBiker]

this is the motor, for the curious amongst you.

i think a new pump would be the easiest option, ive barely got time for the projects ive got going on as it is, rewiring a motor and adding capacitors would get put on the pile and never get done.

 

[6ply]

If it is a synchronous motor. That is how electric clocks kept their time.

But an asynchronous motor (aka induction motor) also depends on frequency, number of poles and slip (?) to determine its rotational speed.

 

[Seadog]

My understanding is that speed of the motor is determined by the frequency and not the voltage. With reduced voltage there would be less power but it should still run.

You are right. I should have said reduced torque. I tested a 380v 3-phase pump and a tool grinder from my standard 240v VFD.

 

[Kram]

Without modification, the pump will run from a 240v 3ph VFD with the VFD output freqency adjusted, to the speed where the motor still produces full torque. Couldnt remember the exact value off my head so looked it up for you, 29 Hz for 230v.

Now my supply, and I believe most of the UK is much closer to 250v and 230v is just on paper to maintain compatability with Europe - its within the tollerance.

However my VFD seems the output is fixed at 220v, you may have to measure or check what your VFD outputs. You'll need between 25 and 35Hz.


This explains it reasonably well

240V Supply to a 400V AC Motor - Application Detail

A 400V x 50Hz motor can be used at 230V x 29Hz when supplied by an Inverter Drive.

inverterdrive.com

 

[daleyd]

You can happily go up to 50 hz on a 230v vfd, albeit it will produce less torque above around 29hz (doesn’t seem to be an issue for a pump).

I’ve got the same pump on my mill (or at least very similar) and I run it off a vfd no problem.

 

[brightspark]

voltage round our way is nearly allways 240v it can drop in out put in rural arias with farms on overhead lines

 

[BrokenBiker]

may purchase a VFD, may get a new pump, depends what will be cheapest and quickest to arrive.

ive got a few jobs need doing that are a bit more urgent than the suds pump though, was hoping to just clean it, stick it on and be done with it but the lathe is currently only 'level enough' on bits of plate and scrap flat bar under each corner, so have got some decent steel to make some levelling feet from, but to get the feet in place i need to make a toe jack set up to fit my 20 ton bottle jack, and while the feet are being fitted i may as well bring it away from the wall a bit more so i can get a brush down behind...oh and the compressor needs a new power switch as that died on me yesterday so cleaning swarf out of the spindle bore and the chucks is getting tedious already wihtout air (again, bloody cheap switches) so for the moment cutting oil in a squeezy bottle will have to do.

 

[addjunkie]

I seem to remember @doubleboost doing a video of running similar on single phase with the addition of a capacitor.

 

[doubleboost]

I seem to remember @doubleboost doing a video of running similar on single phase with the addition of a capacitor.

 

[m_c]

A cheap VFD is probably the easiest and most reliable option.
Just make sure you change the current setting, and it'll be pretty much plug and play.

As @Kram mentions, they should have the relevant setting changed to 29Hz, but if you're running at fixed speed, it won't make much difference.

You can do it with capacitors, but on fractional size motors, getting the phase balance reasonable takes a bit of experimenting and you have less margin for error before cooking the windings.

 

[Turbo]

On a constant loaded motor like that adding a capacitor as a dummy 3rd phase would work nicely.

It's called a Steinmetz Connection and there is a formula for calculating capacitor size but the general rule of thumb is 75uf per kw of motor size.

This video by a forum member explains it all very well.https://www.mig-welding.co.uk/forum/threads/steinmetz-connection.132549/