RE: Variable Ballast

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

Original poster: "Loudner, Godfrey by way of Terry Fritz <twftesla-at-qwest-dot-net>" <gloudner-at-SINTE.EDU>

Hi Greg

The drawback of the helix choke is that it requires a great number of turns.
Putting this aside, a sliding choke can ballast a pole pig. The magnetic
field will pull the core into the coil. One must wind enough turns on a
hollow form such that very little current gets to the pole pig with the core
fully inserted, but enough current gets to the pig with the core withdrawn.
The core is pulled out to increase the current flow. The self-induction of
the coil decreases as the core is pulled out. Such a unit could easy exceed
100 pounds in weight. I have most of the raw materials to build a sliding
choke, but I need to find some literature on the method for calculating the
number of turns. I'm using x-ray transformer laminations for the core.

Godfrey Loudner    

> -----Original Message-----
> From:	Tesla list [SMTP:tesla-at-pupman-dot-com]
> Sent:	Saturday, June 08, 2002 5:04 PM
> To:	tesla-at-pupman-dot-com
> Subject:	RE: Variable Ballast
> 
> 
> I quite like this setup. How does the efficiency compare to that of an
> arc welder or E-I core air gap ballast? You mention sliding the rods out
> of the tube to control current. I was wondering if the rods get pulled
> (due to the magnetic field) into the tube when in operation? If so, how
> do you keep them in place? I would like to make a similar unit and was
> contemplating making the core from chopped up fencing wire.
> 
> Cheers,
> 
> Greg Peters
> Department of Earth Sciences,
> University of Queensland, Australia
> Phone: 0402 841 677
> 
> 
> 
> 
>