Re: shaded pole sync report

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>" <kreld-at-juno-dot-com>

John, all

  I tried a "c" frame shaded pole motor one time, and was able to lock it
at 3600 RPM, but there was no torque left over to run anything.  Seems
like a larger stack "c" frame motor might work, one with a 1" stack
lamination or more.

  I have also done a 1550 RPM shaded pole motor, Dayton brand, 3.3" dia,
1.3 amp -at-115 volt 1/30 HP with plain old bronze bushings.  Only two flats
were made on the rotor, and it works great, locks in at 1800 RPM and will
spin a 4" x 1/4" phenolic disk with four #6 machine screw electrodes for
a 1 kW Coil.   I did use edge mounted electrodes on the disk with a
aluminum band connecting the electrodes, so end play is not a problem.

The 4 pole (1550 RPM) motors do have more torque than the 2 pole (3450
RPM) motors in my experience which might be better for small rotories.

  And no bulky capacitors for the motor to run, some small capacitor
split phase motor cap's are as large as the motor.

> Coiling in Oklahoma

Kevin E.


>All,
>
>I modified a 3200 rpm shaded pole induction motor
>for 3600 rpm sync operation.  The procedure worked, but
>the motor locks at 93 volts with no load, it was barely able 
>to lock with a 3.25" rotor.  It's rated at 2.4 amps.  Shaded
>pole motors are cheap and simple.  A 3200 rpm shaded pole
>motor has only two windings.  It has no run or start cap, and
>no centrifugal start switch, nor any external relay start switch.
>
>The mod was interesting because there is an 1/8" gap between
>pole pieces, and there was a depressed area next to the gap,
>about 7/16" wide.  The armature is 1.5" in diameter.  I first made
>the two armature flats 3/8" wide, but the motor did not sync-lock.
>Next I widened them to 1/2" wide, but it was still NG.  Even 140 
>volts input did not lock the motor.  Finally I figured the flat must 
>need
>to be equal to the total width of the depressed area plus the gap.  
>This is equal to 9/16" total, so I made the flats that wide and the
>motor locked as described. 
>
>For small motors of a given physical size and current rating, 
>a cap run motor is a lot stronger and better for sync modification,
>than a shaded pole motor.
>
>Cheers,
>John
>
>
>