SRSG Phase Controller

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Rob Judd" <canska@xxxxxx>

Has anyone successfully used this phase controller with a larger motor?

My SRSG motor is a 0.5 HP 3600RPM motor... I spent a good deal of time
meticulously taking this motor apart, cleaning it, grinding flats in the
rotor, and making it nice looking. It has performed flawlessly so far and it
sync's hard (no slip) at 105V or higher (I've never gone over 120V into it).

I'd love to make a phase controller for it, but I'm a bit concerned, due to
the description on John's webpage... quote "Larger motors of 1/2HP or more
may exibit a dangerous type of self-breaking [sic] action, especially if the
capacitor is too large."

I do hope that was intended to mean "self-braking", not breaking! Still, its
not good either way.

The only spare variac I have is a 120V 28A Powerstat, and I have some 100uF
320VAC motor run caps on hand that I could network to obtain 50uF, 100uF,
150uF, or 200uF. The resistor and fuse are easily available at RadioShack
like stores, so thats not a problem. Is this do-able, or am I going to
destroy my lovely motor?

Thanks!

Rob Judd - canska@xxxxxx
http://homepage.a5.com/~canska/tesla



----- Original Message -----
From: "Tesla list" <tesla@xxxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Friday, July 15, 2005 4:19 PM
Subject: Re: Help with my rotary gap (and other tuning problems).....


> Original poster: "Harold Weiss" <hweiss@xxxxxxxxxx>
>
> Hi Adam R,
>
> Is the variac hooked up as a variable inductor or as a autoxfmr.  You
> should have it hooked up as a variable inductor with one end connected to
> hot and the wiper connected to the rest of the circuit.
>
> I use a 7.5 A 116U Powerstat with a 40uF motor run cap to drive a 1/20 hp
> hystersis sync motor.  I still need to add or subtract a little to get the
> resonant rise.  I have never blown the 2A fuse, except when I forgot to
> have the motor hooked up, and switched my controller from static gap mode
> to syncronous gap mode. (selector switch)
>
> David E Weiss
>
> >Original poster: "Adam R." <arabraxas@xxxxxxxxxxx>
> >
> >I checked my setup: the fuse to the cap was blown the whole time! Well, I
> >tried again, and the fuse kept on blowing....its a small 2A fast acting
> >fuse, the motor itself is .03A so there shouldn't be a problem. I put the
> >variac in line just by connecting the leads to the numbers 1 and 3
> >(there's five connectors on the variac, 1, 2 ,3, 4, 5...its a small
Ohmite
> >one)..... the fuse still kept blowing. Is the cap value too big for the
> >motor? Plus, in parallel, wouldn't the cap just act as a short? that's
> >what it intuitively seems.