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Re: Giant DC coil to run in Australia

Original poster: syd <tesla@xxxxxxxxxxxxxxx>

Hi Steve,

Yup.. that's what I did. I just responded to Greg's post in a more detailed way, so I'll not repeat myself here.
When the reactance of an inductor equals the current, then no more current can flow. Theoretical lovely, lossless, limiting.
I = E/2 pi f L
Turns out that in my experience that's only accurate for a dead shorted load. In tesla coil practice less inductance (less limiting) is needed for a target maximum current. In my setup for 240v delta, only 3.6mH of series inductance limits me to a current of about 108 amperes.

I designed and built two DC resonant charging reactors (2H each to be used in series) with E/I cores. When I return from Australia I hope to update my web site with the details of that.

I would highly advocate the use of E/I cores in ballast use as well. It is easy to introduce an accurate air gap, easy to stuff a winding in, and fairly cheap with high grade laminations less than 2.00 dollars a pound.

syd klinge

Tesla list wrote:

Original poster: "Steve Conner" <steve.conner@xxxxxxxxxxx>

>It appears that the only thing limiting the charging current is the
>impedance of the transformers and power feed.

As a fan of DC coiling I was pretty interested in the "CAUAC" thing. An
absolutely awesome project and I can't wait to see pictures of the next run.
Anyway I saw the following quote-

"In fact I finally had to stop because my limiters started to smoke; they
were pulling over 100 amps continuous through 8 AWG wire!"

So I assume Syd used three reactors in the three incoming AC lines. If I
remember my power electronics right this does limit the rectifier output
current by introducing "overlap" but it would probably work a hell of a lot
better with a real resonant charging choke. But that charging choke will be
big and heavy (Maybe the $6,800 price included a free truck?)

If you wanted to make your own choke, you could try dismantling a pole pig
and reassembling it with an air gap :^)

Steve C.