Re: Current Limiting and Impedence

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Malcolm Watts" <m.j.watts@xxxxxxxxxxxx>

On 12 May 2005, at 10:27, Tesla list wrote:

> Original poster: "Gerald  Reynolds" <gerryreynolds@xxxxxxxxxxxxx>
>
> Hi Malcolm,
>
> Where can you get Silicon steel?? Do they make welding rods out of
> this stuff or is there another alloy that would work?? and what
> diameter rod should we be looking for??
>
> Gerry R.

Hi Gerry,
          Silicon steel is the material used in transformer
laminations. I can't suggest any shortcuts to getting it any other
way sorry. I'm suggesting making the core using discarded transformer
laminations. You just want whatever material you are using to have as
small a cross-sectional area as small possible to minimize eddy
currents. A tale was recounted some years ago of someone who made a
ballast core from varnished welding rods which got so hot that the
varnish melted. It is questionable whether low-frequency type
transformer iron is really that suited to the job anyway as the gap
is going to throw step functions at it. A PVC tube full of smashed up
N27 ferrites would be a better option. I did this once and built two
such cores.

Malcolm



>
> >Original poster: "Malcolm Watts" <m.j.watts@xxxxxxxxxxxx>
> >
> >Hi Paul,
> >           Whatever rods you purchase for the core, they have to have
> >a very small x-sectional area. They should also not retain much if
> >any magnetism after being de-energized (check with a magnet) or they
> >will have large hysteresis losses resulting in lots of heating.
> >Silicon steel such as used in transformer cores is preferred if you
> >can get them.
> >
> >Malcolm
>
>
>
>
>