Re: [CAD_CAM_EDM_DRO] rotary phase converter

k8zre wrote:

> I need to generate 460v 3 phase from 220v 1 phase line. I have read
> prior posted comments on rotary phase converters. There are a variety of rotary phase converter products both new and used available. Any recommendations, things to look for and things to avoid?? I need drive a CNC mill that is wired for 460v 3 phase. Also using VFD GPD 506 for the head(s).

There may be a way to do this, it depends on the power rating of the motor vs.
the power drawn by the CNC control. You need a dual-voltage motor. Most
dual-voltage motors are wye-wound, because the center tap of one set of
windings is buried, and there are only 9 wires to deal with. If you wire the
motor for 440 V, you have the set of windings that are a completely separate
6-wire set, and the other set with the center tap, and only 3 wires.

Instead of connecting the line to the outer ends of 2 of the line wires as usual,
you'd connect the line to the place where the outer winding connects to the
inner winding. I guess a picture is necessary :



L1---UUUUU---A---UUUUU---CT---UUUUU---B---UUUUU---L2
|
L3---UUUUU---C---UUUUU----

L1, L2 and L3 are your 440 V 3-Phase lines. Connect the 220 V single-phase
line to A and B. The windings between L1 and CT and between L2 and CT
are acting as an autotransformer, stepping up the 220 V line, and making it
seem like a 440 V single phase line is connected to L1 and L2. Note that
the motor should be rated for at least twice the rated load current of the
CNC control, as there will be a lot of current in the path between A and B.
Note that terminal CT is not accessible on most motors, but you don't need
to mess with it, it will be wired right in almost all dual-voltage motors.

Jon