Re: [CAD_CAM_EDM_DRO] Phase Converter

James Owens wrote:

> | You have to make sure the generated line does not vary from
> | the others by much before connecting the CNC machine.
> |
> | Jon
>
> Hi Jon,
>
> I don't understand what you are saying here?

A so called "static converter" as made by Cedarburg and a few others
is nothing but a starting capacitor and some relays. It provides a phase
shift to get a 3-phase motor started, after that, the motor runs on
single phase (badly).

A rotary converter is generally a 3-phase motor and a starting circuit
as above. Depending on the characteristics of the motor, and its
size relationship to the motor to be run, the "generated leg", ie. the
3rd phase that it is generating may vary in phase and voltage
relationship to the other wires, which are your normal 220 V single
phase line. Since you have about 240 V nominally between these
wires, you should also measure 240 v between either of these and
the generated phase. In most cases, there is some difference
in these voltages, and it can become quite large when the load
varies. Connecting motor run capacitors between the generated
phase and the supplied lines helps to balance the shift in voltage.
See Fitch Williams' extensive writings and research on this, a lot of
which WAS in the CAD_CAM files section. It must have been moved
to the archive? Does anyone know where Fitch's rotary converter
stuff is, now?

Anyway, I've heard of wild fluctuations in the generated phase, so it
would be good to make sure your unit is not going to create voltages
that will blitz your CNC control.

Jon