Running Taig motor on 220-240V VFD

[oddodd]

I got a Taig milling head and motor.

Is it possible to run the Taig 1/4 hp motor(115v 60hz) by connecting it to one of those Chinese VFDs with 240v 50hz input?

The electricity system in my country is 240v 50hz.
I understand that using a step down transformer may still cause the motor to overheat or breakdown faster due to the different frequency. The transformer do not convert the frequency from 50hz to 60hz.

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[Eldon_Joh]

VFDs dump more watts into the core due to harmonic losses, so you will have to pay attention to that if you are running that motor near its thermal limit.

i don't machine much aluminum, mostly steel so i'm running below 1/4th hp at the rigidity limit of the machine.

As long as you program the vfd to deliver 2 volts per hz (120vac at 60hz) then you won't have any problems.
If you want to run that motor well above 120vac 60hz then you might back off just a bit on the voltage. 1.8 volts per hz perhaps.

if you want to get really creative, that is a capacitor run motor. meaning it has a second winding in series with a capacitor.
if you remove the capacitor and connect the second winding to one of the other phases of the VFD you should have direction control, and it might perform better..
you might end up burning it out however.

if you have an ac amp meter i would clip it around the capacitor during normal operation.
if you run into very high or very low amps through that capacitor when running the VFD well above or well below 60 hz (keeping 2 volts per hz) then i would attempt to fix this problem either by increasing or decreasing the volts per hz for that part of the curve. (you should have several options available in the vfd)

as far as i know the amps through the capacitor should approximately equal the amps running through the other winding.

but if you only intend to run it at stock speed, just set and forget the VFD to output 2 volts per hz.

[Al_The_Man]

When used with VFD the frequency of the supply is immaterial , the motor does not 'see' the input frequency, it is converted right away to what ever frequency you want to run at.
A 240/120 volt transformer may be prudent, if the motor is rated at that.
Al.

[Al_The_Man]

BTW, this only applies to 3ph motors, 1ph motors will not run on a normal 3ph VFD.
Al,

[oddodd]

Thank you for the information! Very helpful for a newbie like me.

I got the the Taig mill and motor because I wanted something slow enough so I can mill steel and also because I wanted to use ER collets.
I'm not exactly happy with the proprietary collet found on the Kress motor.

[awerby]

It would be simpler to just replace the spindle motor with a locally sourced equivalent, that was already set up to run on your type of power. You might have to adapt the pulleys, but that's not a big deal. If you want to mill steel, you'll need all the torque that the slow pulley setting provides. Slowing down the motor (even assuming the VFD worked for that) doesn't provide as much torque as running it at full speed and reducing that with the pulleys.