Re: Sync Motor Wanted

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

Original poster: FutureT-at-aol-dot-com 

In a message dated 4/17/04 9:41:38 PM Eastern Daylight Time, 
tesla-at-pupman-dot-com writes:

>What sorts of induction motors does this grinding flats technique work for?


The technique seems to work for all typical induction motors.  However
shaded pole motors tend to be very weak, and become even
weaker when modified.  Also some are very poorly made and
may be unreliable.  I prefer to use split phase or cap start or cap
run motors.  Split phase motors have a centrifugal switch inside.
Generally speaking, to drive a given rotor size and
weight, a larger motor will be needed if it's a split phase motor
than if it's a motor with a cap.  Cap start motors have very high
starting torque which helps them to lock sync-ly.  Also cap run
motors seem to give more torque for their size than split phase
motors.  I talk about size rather than HP ratings, because the HP
ratings tend to be arbitrary it seems to some degree anyway.

At my website I show a SRSG using a 6.5" x 3/8" G-10 rotor and
powered by a 1/20 HP cap start (?) Teletype motor.  This motor
was manufactured as a sync-motor.  When motors are manufactured
as a sync motor, they may be a little more powerful than when
modified for sync operation.  For a motor with a 3.3" diameter
armature, I generally make the 4 flats about 3/4" or 7/8" wide.
This would be for a 1725/1750 rpm motor of course.  It will run
at 1800 rpm when modified.  If the same motor is run on 50 Hz,
(instead of 60Hz) it will run at 1500 rpm.

John