Re: Problem with Synchronous Motor and Timing Light

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

Original poster: "Daniel McCauley by way of Terry Fritz <twftesla-at-qwest-dot-net>" <dhmccauley-at-spacecatlighting-dot-com>

> Dan,
>
> You unfortunately may have a hysteresis sync motor.

I hope not.  I know that Dr. Resonance said it was a salient pole synch
motor.

Dan


  This type
> locks into a different position every time it starts, and everytime
> it loses lock.  You need a salient pole sync motor.  These can
> be bought, or made, by modifying a normal induction motor, by
> grinding flats onto the armature.....  2 flats for a 3600rpm motor,
> 4 flats for an 1800 rpm motor.  The width of the flats should be about 1/4
> the armature diameter.  If you have an 1800 rpm motor, and it shifts
> 90 degrees when loses lock and re-locks, that would be normal.
> If it locks to any a spot at any random number of degrees shifted,
> then it's a hysteresis motor.  You can use a hysteresis motor,
> but you have to adjust the phase every time you use the tesla coil.
> This is usually inconvenient, so folks usually avoid the use of those
motors.
> One fellow flips the motor switch on/off a few times until it happens
> to phase up good enough for the coil to run.  I don't favor that
> technique however.
>
> John
>
>
> >
> > 1.  The timing light worked great.  Basically froze the rotor to free
time
> > so you could see the position of the rotor in respect to the 60Hz input
> > power.  However, the problem is that if I briefly touched the side of
the
> > rotor to slow it down just for an instant (yes, it does burn my finger),
the
> > rotor locks in speed again, but in a slightly rotated position and will
> > continue to move about everytime i slow it down for an instant.  Is this
> > normal for a synchronous motor???  I was under the impression that once
> > attached securely to the shaft that it would maintain its relative
position
> > forever unless you rotated the rotor about the motor axel.  What are
your
> > thoughts??
> >
> > Thanks
> >
> > Dan
> >