Bob La Londe wrote:
On 6/14/2018 10:55 PM, Bill wrote:

I was looking at a jointer with a 3HP 3-phase motor.Â* I'd like
to run this from my home which has 220v. Would I be able to run
it on a 20A (preferably) or 30A circuit?

Can you give me an example of a "phase converter" which would
be up to the task?Â* I saw one for $89, but I couldn't tell
whether it would be up to the task or not.Â* I imagine it might
be wiser to avoid 3-phase and keep looking, but I thought I
would check with the experts here first.

Thanks!
Bill


3hp on 220V is (ideally) only about 10 amps.Â* The reality it may
peak a little higher under a hard startup or if you bog down the
motor.

A "good" rotary phase converter is the way to go if you think you
will run much 3 phase stuff.Â* I don't recall the derating, but
its something like 30-40%.Â* ie: Get a 5HP rotary for a 3HP
motor.Â* If all you wil ever run is a motor directly you can
probably go with a cheaper static phase converter.Â* Just remember
that the derating is higher.Â* Its best to see if the MFG says
"This converter will run a X-HP motor."

The easiest way for me (and most expensive) is I have dedicated
variable frequency drives on each 3 phase motor in my shop.Â* When
used 1ph in and 3ph out they have a 30% derating as well, but
they give me infinite variable speed control.Â* Most are on CNC
machines where a 0-10VDC analog power signal controls frequency
and rpm.Â* Others I just use the controls on the VFD.Â* With most
half decent 3phase motors you can run from half speed (frequency)
to double speed without them tearing themselves apart. Â*If they
are inverter rated they may handle more.Â* If you have one of
those fancy new washing machines you probably have a high speed 3
phase motor controlled by a VFD already.Â* You just didn't know it.

Anyway, even with the parasitic losses it will probably run just
fine on a 20 amp 220V circuit.Â* Should be absolutely no issue at
all on 30 amp.

I think 1HP is roughly 750 watts.Â* I always figure 800 and then
add a fudge factor on top of that for safety.

3 X 800 = 2400 watts.
2400 / 220= 10.9 amps.

You will have some loss from your phase converter, heat, wire,
etc. Still with nearly double the fudge factor...

Odds are your 220V is really closer to 230-235 anyway.


Thank you Bob, and to everyone else who responded concerning my
question! Your posts are helpful and informative, and will form
a permanent part of my ongoing education regarding related matters.

Bill