On Sunday, February 19, 2006, at 08:09 AM, Keith Turk wrote:
> Well 2-4 weeks later the poor little old Bridgeport finally runs...
> but not
> without some lessons... ( seems all of life is full of these lesson
> things )
>
> #4 Rotary phase converter ( Anderson Converters )... 3X the HP of the
> Motor... if you use a static converter you lose one leg of the 3 phase
> motor... which is tiny to begin with on mine.
>
> #5 Wiring in the whole deal will cost as much as the Milling machine.
When I was building the autoclave system here I needed compressed air,
so bought a two-stage I-R with 7 1/2 hp 3-phase motor + 80-gallon tank
(surplus auction at the local university -- $550). Everybody else
wanted the single-phase compressors (they went for thousands). We get
our electricity from the local REA -- who didn't have 3-phase wires
near enough, so instead did some magic with the single-phase 7,200V out
there on the pole -- ran it through a transformer for one leg of the
three phase, another xfmr for the other leg, and used the middle for
leg #3 (or someting like that). Not "true" three-phase, but the thing
has run fine* for five years -- and the load is much heavier, I'd
guess, than a milling machine would put on a motor. WAY cheaper than
either kind of converter in acquisition/installation and in operation
(cost of energy -- converters throw a lot of energy into heat and
spinning momentum and a little into the device running off them). If
it's not too late, ask your power supplier if it could do something
like that for you.
* Well, the lights in the building flicker a tad when the compressor's
running, but not enough to do any harm except make it hard to read the
Harbor Freight catalog while sitting in the bathroom. . .
Jon Wennerberg
Seldom Seen Slim Land Speed Racing
Marquette, Michigan
(that's 'way up north)
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