In article ,
Brian wrote:
Thanks, Michael. I'm on your side! I honestly thought that the machines
that I would find available for sale in the 1.5 - 2 hp range would be set up
for the lower voltage, but they are all, so far, 550 volt. Maybe step down
transformers are less common than they used to be or something. So far I've
called on two Excello's, two Bridgeports, a First, and several tiawan
machines, and that's what I've found.

At least *my* Bridgeport (a Series-I BOSS-3 CNC machine) has a
2HP motor which can be wired for either 220V three phase or 440V three
phase. Take a look at the nameplate on the motor -- it should show a
list of terminal numbers to wire for the lower or the higher voltage.

550V seems a bit high for a 440V machine, so these may be a
special winding for the voltage you have. There are advantages to
running on the higher voltage -- lower current, so smaller wire can be
used when connecting the machine.

If it is a Bridgeport, there are places which specialize in
aftermarket repair parts for them, and I had to get a replacement
rotor/shaft for mine -- thanks to some lack of preventive maintenance by
the previous owner. :-( They list a lot of different repair parts for
the head and motor, and if all else failed, you could probably get a
replacement stator, with the lower voltage windings -- or you could get
the existing stator re-wound for 220/440V. Either route would probably
be cheaper than getting a transformer to step 220V up to 550V followed
by a (more expensive) VFD for 550V operation. (Or a rotary converter
made from a 550V motor, with more expensive capacitors because of the
higher voltage requirements.

Good Luck,
DoN.
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