RK05 spindle pulleys - trade 50Hz vs 60Hz?

[Eric Smith]

On Wed, Jul 25, 2018 at 7:54 AM, Paul Koning via cctalk <
cctalk at classiccmp.org> wrote:

> > On Jul 25, 2018, at 9:50 AM, GerardCJAT via cctech <
> cctech at classiccmp.org> wrote:
> >
> > Why don't you simply power it through an inverter that will output 60
> Hz, eventually even "down to" 120 V , true sine wave, of course ??? They
> are not that expensive by now.
>
> I wouldn't worry about "true sine wave".  That seems more of a marketing
> thing anyway, and motors don't care.  Just feed them with a variable
> frequency motor drive and all should be well.
>
> > And be carefull : motor designed for 60 Hz, running "under" 50 Hz, OR
> THE OPPOSITE, I do not recall  !!!, display a significant reduced life time.
> > I have to check which is which, but I know this is a question of
> saturated magnetic field. Better check first.
>
> That doesn't sound right.  If you run the frequency up high enough you
> might get into problems with magnetic materials not designed for it.  And
> much lower probably gives you reduced torque.  But 50 vs. 60 Hz is a
> trivial difference for a motor, I can't see any reasons for that to cause
> trouble.  I routinely run my lathe at half frequency if not less, and it
> doesn't complain.
>

I'm not sure about motors, but 60 Hz power transformers can't handle as
high a maximum power (or current) when used for 50 Hz. The maximum power
has to be derated. Some transformers are specified/sold with a single power
specification for both 50 and 60 Hz use, which just means that the vendor
has built the necessary derating into even the 60 Hz specification.

Some products were built using different transformers for 50 vs 60 Hz
models, and the 60 Hz models uses a transformer inadequate for 50 Hz
operation.