Re: A few questions

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

Original poster: "Jim Lux by way of Terry Fritz <twftesla-at-qwest-dot-net>" <jimlux-at-earthlink-dot-net>



Tesla list wrote:
> 
> Original poster: "Jason Johnson by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <hvjjohnson13-at-hotmail-dot-com>
> 
> Well I've had a few questions in the back of my mind for a few days now
so here
> goes:
> 
> 1. I have two nice 0-75 amp AC ammeters with 5 amp full scale movement.
Thus I
> need 75-5 (15-1) current transformers. I also have two 150-5 (30-1), but no
> 75-5 current transformers. Since my CTs are twice the size I need can I just
> wind two turns in the winding window on the CT? I'm assuming that this is how
> you hook them up (they are square shaped with two terminals on top and a 2"
> hole through the middle) and that they only normally have the hot line
passing
> through the middle.

Exactly... two turns gives you half the current ratio.



> 2. Could a three phase transformer be run from a single phase to three phase
> converter for motors like the one here
> <http://www.metalwebnews-dot-com/howto/ph-conv/ph-conv.html>http://www.metalweb
> news-dot-com/howto/ph-conv/ph-conv.html

Yes, and if you wanted to run a DC coil, three phase might be real
attractive.  Consider though, the weight and size of the rotary
converter+transformer against a single phase transformer of the same
rating.  However, if you get one for free or cheap, then....

> 
> 3. What would a "tripolar" tesla coil look like (like a bipolar but three
coils
> run on three phase) i.e. spark behavior, appearance?

An interesting question, but a tripolar coil wouldn't need 3 phase AC
power.  It's the phasing of the RF that makes a bipolar (or tripolar) coil
what it is.  You could run 3 coils with static gaps, one off each phase,
and you'd get an interesting effect (essentially the sound of a 360 Hz
break rate).

To get a true tripolar coil, it would take a bit of fancy figuring to get
the tank primaries and capacitances worked out to get the phasing right,
especialy to run it off one gap. Maybe something like a Scott-T implemented
with air core transformers? or a goniometer setup?  If you had three Vacuum
tube coils, then you could probably do it by running only one as an
oscillator, and driving the others as amplfiers. (Hey Terry, you have all
those signal generators and ARBs).  With a good timing system (better than
1 uSec accuracy needed) and three triggered static gaps, you might also be
able to fake tripolar (fire the gaps 1/3 cycle time apart)
> 
> Jason Johnson