On Thu, 03 Jul 2008 21:39:46 -0400, Wes wrote:

Uncle's 5hp single phase motor for his A.O. Dobbs table saw (big sucker) croaked on him so
he went down to the scrap yard and bought a 5 hp 3 phase motor.

I looked at the partially marked wires and the data plate and did my best to figure out it
was low voltage wired. Tip is that 3 wires together. From what I can see, your normal 3
phase motor has once set of windings internally connected to form a wye. From there you
either add in series another winding to each leg of the wye for HV or you build another
wye out of the three other windings and parallel them.

Ohming the windings did not find any shorts to ground. Uncle meter sucks so I can not
tell if a winding is shorted to itself but not to frame.

My first thought is maybe each wye isn't properly oriented to the other one.

My second thought is disconnect all the wires, find the three that are internally
connected and attach power to just those to test the motor. I would think it would make
it a 2 1/2 hp motor that would get him by for a while.

My third thought is to play with the other 6 wires and make another wye trying
combinations to see if those can run it.

The forth thought is if I can get set 1 and set 2 to run the motor, try the 3 arraignments
of paralleling them to get the 5 hp.

Are my thoughts right? Thanks,


Wes


Buy a box of fuses!

Find the wye connected set and isolate the remaining 3
pairs.

Run the motor unloaded on the wye set.

Experimentally connect one remaining pair to a single wye
radial.

If there is no significant change in motor current or
noise this is an OK connection.

If the motor becomes obviously distressed or blows the
fuse reverse the connection.

Repeat trying the second remaining pair sucessively on
each of the remaining two wye radials.

Of the 4 possible ways of making this connection, one way
will correctly parallel the winding and result in a smooth
running motor.

Repeat with the third remaining pair on the remaining wye
radial.

Good Luck !

Jim