Re: Motor Sync Problem

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

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

In a message dated 9/27/01 8:15:24 PM Eastern Daylight Time, tesla-at-pupman-dot-com 
writes:

> I wonder if there is a relationship between apture diameter and
>  optimum flat width.  If the flats are too thin the motor has
>  difficulty syncing, too wide and it draws too much current and loses
>  HP.  There should be an optimum width, correct?  By grinding flats a
>  little at a time and taking measurements of lock voltage and available
>  HP, you should be able to determine a relationship.  I could probably
>  do a study like this if it would be beneficial, just give me some
>  recommendations.

Ryan,

A number of folks have done that, and it led to the present
recommendations.  I can't remember if anyone tried it for
3600 rpm motors, but they probably did. There may be factors that alter the
diameter relationships for various motors, but I'm not sure.
What's interesting, is that the width is usually not that critical,
especially when the motor is not loaded.  For example, I would
have expected your motor to lock right up at 50 - 70 volts even
if the flat is a little narrower than optimum.  This is what made
me think that maybe the flats for 3600 rpm motors have to be
wider than for 1800 rpm motors, but I don't really know.

>  Actually, because I had nothing better to do that night, I tried
>  forcing it to sync.  As I increased above 120v it slowly got closer
>  and closer to sync but even at 140v it wouldn't.  At what voltage
>  should a properly milled motor sync?

Often they sync at 40 to 70 volts with no load, or a very light
load.  Various motors seem to behave very differently for
some reason.

John

>  
>  Thanks again!
>  
>  Ryan Phillips
>