Re: Interesting inductor observation

["Luc" <ludev-at-videotron.ca> (by way of Terry Fritz <twftesla-at-uswest-dot-net>)]

Hi all

We had done some experimentation at job; we need a good variable ballast for
testing various equipment's ( TIG, motor, discharge lamp, ect ) at first we try
variarc but we experience trouble: sometime oscillation, no linearity. We
have a
big winding with a lot of tap retrieve from a big transfo: work good but
too big.
Finally we build a strait coil with a lot of tap and a moveable laminated core,
that work good. Could be cool to have one like that at home.

Luc Benard (Montreal)

Tesla list wrote:

>
>
>         I agree completely.  Apparently the "gentleman" doesn't know what
he is
> talking about, or has been quoted incorrectly.  An inductor IS indeed an
> inductor period.  Assuming core saturation is really not a factor, that
> is.  I have always been suspicious of the use of a Variac as a ballast,
> unless there is a pretty big air gap in it.
>
>         Someone suggested using air-core ballast inductors.  If you can
afford
> the wire it would take to make a coil of suitable inductance and current
> rating that would be a fine idea.  I would think the resistance would be
> small enough not matter if the wire could carry the current.  Somewhere
> (I can't find it when I want it, of course) I have a copy of a
> University of Illinois Experiment Station Bulletin from the early 1930's
> advocating the use of air-core inductors. Includes a lot of design
> information, including discussion of optimum geometry.  I'll try to run
> it down in case anyone is interested.
>
> Ed