On Mon, 24 Sep 2007 21:38:33 -0400, clare at snyder.on.ca wrote:

On Mon, 24 Sep 2007 09:58:00 -0700, Bruce L. Bergman
wrote:

On Sun, 23 Sep 2007 20:03:22 -0500, "Camilo Ramos"
wrote:

On Sun, 23 Sep 2007 07:22:04 +0000, Karl Townsend wrote:


Here's a good chance to upgrade to variable speed. Install a three phase
motor and VFD. 3 phase motors can be scrounged for cheap/free. Iggy has VFDs
for small motors real cheap

Yes but first I'd like to get a method to test any motors at the dumpster
itself without actually having to look for a way to connect to the mains.
Plus, often motors ripped out from God knows where have no markings on
them, so connecting the wires becomes a guessing game.
Oh, and I dont have 3-phase only single so I would need to build a pahjse
copverter

You could always buy a "Megger"® hi-pot insulation tester, that
should catch the motors that are totally bad right at the dumpster -
but for one problem.

You'll pay more for the testing tools to find out if the windings
are bad than you would for a brand new electric motor that will be a
precise drop-in fit, with a warranty, from a supply house.

Most motors under 5 HP (and almost all under 2 HP) are usually found
in the dumpster for a /reason/. Either bad bearings, start switch,
start or run capacitors, or winding problems. Better yet, if you are
in a rush to open it up and fix it, it's really easy to try fixing one
problem and cause another and the machine will fail again...

And in an industrial production setting it's far cheaper to toss the
bad motor than to futz with repairing it - when that machine isn't
making parts, you are losing money, period.

If you can collect three or four identical motors with different
faults from the same dumpster, you can swap bits around and make a
good one. But you'll waste a lot of time doing it. If your time is
essentially free, go for it.

-- Bruce --


The vast majority of 3 phase motors I find in the scrap are there
because the equipment they were on was obsolete and it wasn't worth
saving the motor.


Indeed. I think Ive found (1) bad motor in all my scrounging. And it
was only bearings.

Gunner