Re: [CAD_CAM_EDM_DRO] Rotary vs. Static Phase Converters

fuddham@... wrote:

> I am buying some used CNC turning centers (3 phase power). I only
> have single phase power at the garage. Can I run the turning centers
> (10 hp motors) with a static converter or do I have to use a rotary
> converter.

It depends. If the spindles are simple single speed (60 Hz) AC motors,
and all other loads (CNC control, axis drives) are single phase, then you
can, but you will get reduced torque, and possibly the spindle won't
start at the highest speed settings.

If the spindle drive is an AC variable speed drive, or the axis drives or control
run on 3 phase, don't even think of it, the smoke that will gush out of it
will kill you before you even realize how much it will cost to repair!

Now, some AC VFD's will run at reduced capacity on single phase,
but if they have 3-phase transformers running the axis drives, they
will almost certainly overheat, and the 'static converter' (really a
starting relay and capacitor) will do horrible things to them.

Most CNC machines specifically state in the manual that use of ANY type
of phase converter voids the warranty. A really well-balanced rotary
will probably work, but a badly balanced one could cause overvoltages
when the spindle starts or stops that could fry things.

Jon