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racktech2008
18-03-2008, 04:38 AM
Iīve trying to find the exact replacement motor for a Witt Lo Flo walk-in cooler evaporator but so far not so good. The only model available that would fit in the bracket turns the opposite way. I thought I could find a blade that would perform as the original, but blades are also unavailable with the required reversed rotation. These motors are really small, I guess shaded-pole type since they donīt have a capacitor. Is it possible to reverse the rotation of these motors by somehow reconnecting the windings?

paul_h
18-03-2008, 05:31 AM
Shaded pole motors are usually reversible by putting the roto in the opposite way.
But walk in coolers dont usually use shaded pole motors as they aren't powerful enough :confused:

monkey spanners
18-03-2008, 08:15 PM
If you take the motor to bits, aluminium ends with a laminated iron middle, and its a shaded pole motor you will see the thin gauge copper windings and two or four copper shading rings (really heavy gauge copper 2-4mm) looping through the laminations on two sides. These cause the magnetic field to lag that in the unshaded part of the laminations and thus cause a rotating magnetic field instead of an alternating one as would be the case without the rings. As Paul h said, just build it back up with the spindle on the opposite end. The cable will now exit the motor nerest the spindle. On the one i did there was a knockout cast into the spindle end aluminium end, just knocked this out, built motor back up and put some silicone sealer in the now non used hole at the other end.

If its not a shaded pole motor it will need a capaitor, centirfugal start switch or to be three phase for it to start the correct way every time. If it is a capacitor motor, it may be posible to run it the other way by wiring it diffrently.

Jon

racktech2008
19-03-2008, 01:30 AM
Thank you very much for your kind responses. I did exactly what you both wrote: took apart the end bells, relocate the rotor, re-assemble the unit. The motor is now rotating just like the original.
This motor really is a shaded pole: no capacitor or centrifugal switch, just windings. Itīs an AO SMITH model no. 574, 1/20 HP, 115 V, 1.5 amps.