options for powering 440v motor

[scudzuki]

I may need to provide 460v 3 phase power for a lathe I just bought.
I have a 10 HP Phase Perfect which provides 230v 3 phase.
I also have 230v single phase available.
If I cannot rewire the motor for 230v, what are my options? Are there VFDs that can transform voltage as well as create 3 phase? Are there (relatively) inexpensive 3 phase transfromers available?

Thanks in advance.

Joe

[mactec54]

scudzuki

You would first have to get a Transformer, that will go from your 230 to 440 rated for the amps that you will need for the motor, you then would use a 440V VFD

[mike_Kilroy]

3ph 230-460 xfmr probably best choice off ur phase perfect if >3hp motor on new lathe. we normally just use motor HP=kva to size it - so 10hp motor would have a 10kva xfmr typically.

u can keep cost down by buying an autoxfmr instead of iso xfmr; a 2:1 auto will be same size as 1/2 the kva of its equiv iso xfmr so therefore prob around 30% lower cost.

what is rating required on the lathe? for instance, I would guess a new 5kva iso xfmr in nema 1 box to set on floor next to machine around $ 750; auto 5kva maybe $ 500. I could quote you new of course but you can likely find good used one locally for 1/2 the price of new.

[scudzuki]

There's no question the 10 HP PP will provide sufficient power for the 5 HP lathe. I ordered twist lock plugs and a receptacle so I can switch between my VMC and the lathe.

There are only 6 leads coming out of the lathe motor (labelled a1 a2 b b2 c1 c2) rather than 9 like the 3 phase motors I've seen in the past so I'm not sure if it can be rewired for 220v. It might be cheaper to just replace the motor, but then I may have to replace the contactors since that will double the current requirement.

3 phase transformers come up for sale from time to time. If I could get one for a reasonable price (no offense, $750 is not what I consider reasonable... that's what the lathe cost) that may be the cheapest and easiest route.

I have schematics on the way so that may shed some light.



Joe

[mactec54]

scudzuki
I think you will find that the motor on the lathe is a 2 speed,That model mostly had a 2 speed motor, I would try & find a 230v motor & run it with your Phase Perfect

[Al_The_Man]

It could also be 6 leads for Star-Delta, many UK and European motors are supplied this way.
See if you have 3 distinct and separate windings, if so you may be able to run on 240v Delta.
Al.

[scudzuki]

Originally Posted by mactec54 scudzuki I think you will find that the motor on the lathe is a 2 speed,That model mostly had a 2 speed motor, I would try & find a 230v motor & run it with your Phase Perfect

Correct, it is a 2 speed motor.
How is that accomplished?
I thought AC motors were sychronous?
There is no vfd and no transformer in the cabinet large enough to transform 5 HP so it must be some trickery manipulating the timing of poles in the motor? I suppose there are 6 poles and for the higher speed adjacent poles are combined and for lower speed all of the poles run independently? If that's the case can't it be bootstrapped by running adjacent poles in parallel to half the voltage requirement?

I guess I should have included that pertinent information in my initial inquiry... seems like that changes everything.

I have found a reasonbly priced 3 phase transformer (reasonable but still over $200 shipped) that in theory would allow me to provide 460 60 hz but since the unit has not run in possibly a decade I'm hesitant to spend the money. Definitely safer spending a bit more and getting a 230v motor and new contactors. There's also a coolant pump to replace but I can do without flood coolant initially. The biggest downside to replacing the motor is that I will lose the range the 2 speed motor provided unless I spend even more $$$ and get a VFD. Decisions decisions.

Joe

[mactec54]

scudzuki

Get a motor & a VFD, To get it going you may be able to wire it to run on the 240Volt
it should be just a 4 pole motor it will be on the tag, they use 2pole for the higher speed

[scudzuki]

I found a 30 kva 3 phase multi tap transformer on ebay.
200v or 220v in @ 50 or 60 Hz
380, 415, 440, or 480 out

My 230 is actually 238 so I tapped in at 220 and out at 415, actual output 442v.

YouTube - Call me Sparky
Joe