Re: SRSG motor modification

["Garth van Sittert" <garth-at-mediasupplies.co.za> (by way of Terry Fritz <twftesla-at-uswest-dot-net>)]

Thanks everyone for the replies!!

I tried a 20uF and then 40uF and 68uF but no luck.  The motor certainly did
spin up faster though at the expense of drawing about 5A while running.

Yes I was pondering the same thought about the wwwwWWWWWwwwwww noise (as you
so aptly described).  That noise occurs only if I load the motor quite a bit
by holding my hand around the spindle. (Very dangerous as the electrodes are
1/2 inch from my fingers and at that rpm ......).

How does the cap size affect the motor once it is running at full speed.  I
thought it only effects startup torque.  Or does it phase shift the smaller
windings during a run for more 'synchronous' control.

The pictures are now up for anyone to see if I am doing something wrong.
http://teslacoil.8k-dot-com

Thanks again for all your replies.  And many thanks to kVA effects for the
excellent graph and explanation on the 200+ BPS.

----- Original Message -----
From: Tesla list <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Wednesday, August 09, 2000 8:10 PM
Subject: RE: SRSG motor modification


> Original poster: "Colin Dancer" <CMD-at-datcon.co.uk>
>
> I'd second the suggestion to use a larger capacitors, but you need to be
> careful not to go too far.  If you make the capacitor too big, you can end
> up with the phase in the secondary winding nearer 180 degrees out of phase
> rather than the 90 degrees intended.  I found that with a 20uF capacitor
> (rather than the 4uF original) my motor ran raggedly at 1500 rather than
> 3000 rpm!
>
> If you motor is close to but not quite locking it should be making a
whining
> sound with a 0.5s - 3s period (as it gets near to lock and then slips).
>
> Kind of like,   wwwwwWWWWW.....wwwwwWWWW......wwwwWWWW....  :-)
>
> If that's the case, then it might be worth trying to get an lock using a
> variac to boost the initial voltage.  I found only an extra 30V was
required
> to get my 1/4HP motor to lock with a 6"disc, and after lock I could reduce
> the voltage back to 240V.  It's also worth trying for a lock without your
> disc attached.  If it won't lock with no disc then it's never going work
> when you add the extra drag of a rotor plus flying electrodes.
>
> Regards,
>
> Colin.
>
> P.S. A number of the images on your website seem to be zero length files
and
> I wasn't able to load the picture of your motor.
>
> -----Original Message-----
> From: Tesla list [mailto:tesla-at-pupman-dot-com]
> Sent: 08 August 2000 18:41
> To: tesla-at-pupman-dot-com
> Subject: Re: SRSG motor modification
>
>
> Original poster: FutureT-at-aol-dot-com
>
> In a message dated 8/7/00 4:47:35 PM Pacific Daylight Time,
tesla-at-pupman-dot-com
>
> writes:
>
> > Original poster: "Garth van Sittert" <garth-at-mediasupplies.co.za>
> >
> >  Thanks for replying.
> >
> >  The motor is 1/4 HP or 180W
> >  2850 rpm 50Hz
> >
> >  My armature measures: 4" long,  2" diameter.
> >
> >  The 2 flats I have made are 1" wide.
> >
> >  I have pictures of it at http://teslacoil.8k-dot-com/spark_gap.htm
>
> Garth,
>
> I tried looking at your webpage, but the pictures didn't load for
> some reason.  In any case, I'm thinking that maybe you need
> to use a larger capacitor than 6uF,  you could try larger ones
> such as 10uF or 20uF, and see it that makes it lock up OK.
> The flats should be plenty deep enough the way they are now,
> by the way.
>
> Cheers,
> John Freau
>
>
>
>
>