On Wed, 31 Mar 2004 04:33:45 +0100, LRod
wrote:

On Wed, 31 Mar 2004 02:23:53 GMT, "Edwin Pawlowski"
wrote:


"LRod" wrote in message
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)?

Delta claims their contractor saw motor is 1.5 HP on 115V and 2 HP on 230V.
How does this figure into the series/parallel in the windings? Or whatever?
Ed

Frankly, I don't believe Delta's claim. But I'm not a motor guy.
However, I'll ask someone who is. He's a regular poster on a couple of
the woodworking fora and probably the smartes person I know on this
subject.

I did some more checking around. First there was an article following
up an article in Popular Woodworking. Although there's still some
misinformation in it, at the very bottom there is a reference to the
Delta conundrum: http://www.popularwoodworking.com/features/240V.html
Basically, Delta says there is no performance difference between 115V
and 230V, although they didn't specifically address the different
horsepower claims.

My friend replied with an entirely different perspective that I think
hits the nail on the head:

A NEMA 5-15 duplex single phase 115 Volt wall outlet is rated for 15
amps. The max electrcial power a single phase induction motor can draw
from a 15 Amp 115 Volt outlet is equivalent to the demand of a 1 1/2
HP honestly rated induction motor.

An honestly rated single phase 2 HP motor on 230 volt power typically
draws 11.5 Amps full load current. If connected for 115 Volt, the max
current the motor can be rated to draw from a NEMA 5-15 duplex is 15
Amps. However the motor run to full load ratings could draw 23 Amps.

Let's say some damn lying marketer seeking any conceivable competitive
advantage and an ethical electrical engineer and a tort lawyer had a
meeting to hash out just what claims could be made for a motor U prong
NEMA 5-15 duplex walloutlet. They had to hash out just what could be
safely claimed for their dual voltage cord connected machine and still
satisfy their recent class action suit judgement.

Their decision could be to rate the motor as 2 HP at 230 Volts and
de-rate it to 1 1/2 HP to meet the UL limits of the Wall outlet. Dumb
but bureaucratic.


I'd wager lots of money that's the answer. They're not claiming MORE
hp at 230V; they're claiming LESS at 115V. Tricky.


- -
LRod

Master Woodbutcher and seasoned termite

Shamelessly whoring my website since 1999

http://www.woodbutcher.net