Can't use VFD only rotary?

[QSIMDO]

Got real interested in a milling machine today but it's 3 phase and will only run with a rotary phase converter and not a VFD.

Would anyone know why offhand?

The tech folks were friendly but had no further information.

[thistle]

Got real interested in a milling machine today but it's 3 phase and will only run with a rotary phase converter and not a VFD.

Would anyone know why offhand?



The tech folks were friendly but had no further information.

Presumably it has auxiliary motors such as power feed and coolant pump,and also control contactors,all of course would be fed from the same power source.

A rpc can be considered like mains power in this respect.


A vfd could not run all of the differant motors ,each motor would need its own vfd ,also the controls would have to be reworked ,or eliminateed and replaced to be compatible with the vfd.

[IOWOLF]

Ummmm. cause the RPC costs more than the VFD, or they don't sell VFD's .

[QSIMDO]

Presumably it has auxiliary motors such as power feed and coolant pump,and also control contactors,all of course would be fed from the same power source.

A rpc can be considered like mains power in this respect.


A vfd could not run all of the differant motors ,each motor would need its own vfd ,also the controls would have to be reworked ,or eliminateed and replaced to be compatible with the vfd.

That's what I thought as they offer this mill either plain at a very nice sale price or "peanut" with DRO and power table feed.

So anyway I asked if the base model would run OK with a VFD and they said "nope, they all need RPC."

I think I was gettin' zoomed as in IOWOLF's response.

[John Stevenson]

Over here if we have a machine that runs a 440v 3~ two speed motor then these need 440v 3~ from either a RPC or a static.
Rewiring to delta to run on a 240v VFD can be a pain and you loose the other speed.

Often more trouble that it's worth.