Re: [CAD_CAM_EDM_DRO] Re: Home shop power for a big machine - Thanks for the ...

In a message dated 1/3/2009 8:29:12 A.M. Central Standard Time,
rob@... writes:

The cost of running it are so small, that I'm considering buying a 3 phase
lathe instead of 220v.<<
Rob, that's the ONLY way to go, if you don't have 3-phase "from the pole"!
A 3-phase REVERSES very simply, has equal torque both ways, makes less racket
when starting/stopping, is a less-expensive motor (for same hp/speed), etc.,
etc. Besides, all the "better" machines —— read "professional machines" ——
COME with 3-phase motors.

A tip from a "residential shop owner": If you have had only single-phase
for a time, or, are moving into a new place and don't KNOW, yet, go "out back"
and look where your electrical power connection from the "meter can" (=where
the glass-enclosed KWH meter is mounted) to the pole. Are there TWO or THREE
transformers? At least, are there at least TWO "high-voltage primary lines"
from pole-to-pole, not counting the "ground line" which is usually the one
on the very TOP ENDS of the poles? If so, then you have 3Ø "at the pole," and
all you have to do is pay your utility a little extra money (ONE time!) to
drop that third wire to you! Pray they don't have to add the second or third
transformer, or increase the size of those already there, to add YOUR load
(some serious $change can result from that!) You would have to have an
electrician prepare your "utility entry" for 3 phase, and install a "3 phase meter
can" (which the utility will supply him; the electrician knows how to get
those).

Whether TWO or THREE transformers ("open delta" or "balanced 3 phase") is
beyond the scope, here, but for MOST machines, the resulting "3 phase voltage"
difference, 240-between legs, or 208-between legs either makes insignificant
difference, or, there are "taps" for the different voltages on the motor
terminals, etc.

I was lucky to move where the utility-line behind our house/shop is shared
by a private school which had 3-phase for their air-conditioning, so it was
straightforward to "drop" it to me, as well. I had to pay $1500 for the
utility to increase all the "pots" 5KVA to add my load, but that was less hassle
than a phase-converter, separate wiring and keeping track of which went to what,
etc. when I wired the new shop I built. So, any machine with a motor
larger than 1/4 hp. has a 3-phase motor. MUCH BETTER!




Sorry for the rant. HOPE it is usefully-informative. Jan Rowland,
Home-Brewer and amateur machinist
**************New year...new news. Be the first to know what is making
headlines. (http://www.aol.com/?ncid=emlcntaolcom00000026)


[Non-text portions of this message have been removed]