380V 3 phase motor on 220v 3 phase

Hi all
Looking for some help on a motor i have bought. on the name plate there is only one voltage for 380v
Its a two speed motor and has both delta and wye symbols.
Can I run this motor on a 3 phase 220v VFD. Would i lose much power if it can be done.
I don't need to run it at the two speeds so if only one speed is possible i could live with it.
Any help on this would be much appreciated.

Read this thread:
Inverter 240v 50hz 1 phase into 415v 50hz 3 phase

I'm going to nudge this thread because I have a motor by the same maker. I already have a VFD for 220V 3 phase and if it's possible to wire this to operate from it, would allow me to maintain all of the pulleys and accessory drive.

I keep seeing the "380V 3 phase motor off 220V single phase" and that spooks the heck out of me.

That inverter may be a way to boost the voltage, but the cost is prohibitive, so let's hear if there are any viable options to use what is there.

https://www.practicalmachinist.com/vb/attachment.php?attachmentid=256707&d=1558143838

https://www.practicalmachinist.com/vb/attachment.php?attachmentid=256708&d=1558143860

Hopefully there is a way to get this operational. I have an antiquated transformer to take the 220V to 440V, but I would prefer to avoid using it for this application.

Let's see those electrical engineers strut their knowledge of 'trons

Mark

Crank said:

Let's see those electrical engineers strut their knowledge of 'trons��

Click to expand...

I'm surely not one of those guys ! But have been told by one that 380v 50 hz is equivalent to 440/460v 60 hz. I have never tried it but always wanted to. Rpm would be different but otherwise .. ?

Emmanuel,
That is a true statement, but that's 440V and I'm wondering if there is a 220V option to pursue. We'll see what the experts have to say. Most likely, I'll get a 3 phase 220V motor and forego the aggravation.

Mark

Motors create their rated torque based on their design ratio between voltage and frequency (V/Hz ratio) and are generally fine for anything within 10%. Outside of that +-10% window, running torque drops proportionately but more importantly peak torque varies at the square of the change. Peak torque is what your motor uses to accelerate a load and REaccelerste it after a change in load, ie putting a bit to a workpiece.

A motor designed for 380V 50Hz has a design V/Hz ratio of 7.6:1. If you give it 220V 60Hz, that’s a V/Hz ratio of only 3.67:1, less than half (48%). So your peak torque will be reduced to only 23% of what the motor is rated to deliver, running torque will be at 48%, but only IF the motor can get to full speed, which it may not.

If instead you buy a simple transformer and step the 220 to 440V 60Hz, your V/Hz ratio becomes 7.3:1, which is within 4% of design. Your motor will run just fine, albeit 20% faster.

Also, “220V” is uncommon, most utilities began delivering 240V decades ago, people just never changed their descriptions. There are a few pockets of actual 220V still, but only in “legacy” systems where the utility is too small to afford to modernize.

Jraef,
Thank you, for an explanation that is clear and understandable by one as limited in comprehension as myself. To clarify for myself, with the needed ratio for V/hz, the approximate ratio for 240V would be in the ballpark of 31hz. Would I be correct to guess that the motor would run at a significantly reduced RPM than identified on the plate? That being the case, I have a wonderfully built motor that doesn't warrant the monetary investment, nor the additional bulk of a transformer. My needs are merely to power the lathe at its designed speeds, with virtually no expectations to use the drive for the grinding attachment. If needed, I could attach an auxiliary motor to drive it.

I truly appreciate your answer and it has helped me to decide if I should continue to chase windmills or not.
Thanks

Mark

I'm always looking at HGR Surplus for cheap items. I get a lot of good deals but some junk too. From time to time I see 380VAC transformers, have no interest in them so I never check the details. They drop the prices on items as time goes by and it's not selling. Transformers with odd voltages usually wind up being sold very cheap and near scrap value. Your motor don't look very big so a small transformer shouldn't be expensive to ship UPS. If your not in a rush check them out, sooner or later they will have one.

I already have a transformer. It's not huge, but it weighs 70-80lbs. This is my lathe for little work and I don't want to add to the bulk for the footprint of this lathe.

Hands down, since I have a brand new 2hp VFD already sitting in a box, I can source a new.motor for very reasonable cost. It just seems wasteful to have such a quality motor, already set up with a clever drive system and lack a simple means to keep it in service. The huge benefit of a replacement motor on a VFD is the elimination of the bulk and complexity of that same clever drive system.
Thanks

Mark

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