On Wed, 31 Mar 2004 01:22:05 +0100, LRod wrote:

On Wed, 31 Mar 2004 00:08:22 GMT, Phisherman wrote:

On Tue, 30 Mar 2004 09:32:00 -0500, "Denis Caissie"
wrote:

What are the advantages of a 220V connection vs a 115V connection for power
tools?


A motor running on 220v will start up easier,

Maybe. It depends on the stiffness of the power source (a 115/20A
motor on a long 12 guage run won't "snap to" as nicely as when it's
sourced with 230V and only drawing 10A). I understand this to be due
mostly to the phase shift from the start capacitor, but I'm no
engineer. But it's also partly due to the high, yet short duration,
current draw (and associated I^2*R losses) at startup.

Yup


run smoother/quieter,

Nope. Supply voltage has zero effect on smoothness or quietness. See
dual voltage discussion below.

Yup


last longer,

Why? Most dual voltage motors run on windings wired series/parallel
(windings are in series with a source of 230V; parallel with a source
of 115V). In other words, regardless of how they are powered the
windings are always seeing 115V. So how would a motor running with
115V on its windings last any longer than a motor running with 115V on
its windings (or run any smoother/quieter)?

Well, cuz of the old I^2*R effect in the windings, there will be only 1/4
as much heat generated in the windings and...


run cooler,

Same as above, except if the supply on 115V is marginal on capacity.
And in that case, the argument could be made that the heat developed
from the less than optimal voltage *might* contribute to shorter life.
However, that anomaly could as easily be remedied by stiffening the
supply as changing to 230V operation.

....it will run cooler.


use less energy than the motor running on 120v.

Nonsense. Watts is watts. A motor running on 115V @ 20 amps uses exactly
the same amount of energy as a motor running on 230V @ 10 amps. P=IE.

Yup (within a red one)


The differences are more pronounced with larger motors.

Nope. Except in conjunction with a supply that is less than optimum (15A
circuit instead of 20A or 30A). In that case you're right if you compare
a 2hp motor with a ¼hp motor. But who uses those outside of squirrel
cage fans? That's not what we're talking about anyway.

Yup


It's all about the supply. If you had a typical 2hp dual voltage motor
and ran it on an 8 g, 40 amp circuit, you would likely see ZERO
difference in performance whether wired for 115V or 230V.

Yup (within a red one)


You won't usually see motors much larger than 2 hp that are capable of
being wired to run on 115V.

Yup



- -
LRod

Master Woodbutcher and seasoned termite

Shamelessly whoring my website since 1999

http://www.woodbutcher.net

-Doug

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