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Re: Controling a Pole Pig
Stephen,
I am not as experienced as others on this list, and I have not used this
design,
and I will be interested to see what some of the wizards advise; but I have
one
concern that I hope either you have already resolved or someone could clear
up.
I get the impression that you will use the 240 as the primary and still
have the
11kV windings present as a secondary; won't this intoduce an LC component into
the circuit? I hope this isn't an ignorant question.
Bryan Kaufman
Tesla List wrote:
> Original Poster: Steve Rodway <Legion-at-legion-elec.demon.co.uk>
>
> Tesla List wrote:
>
> > Steve
> > > I do have a related question though, I have 2 pigs, and was
wondering
> > if I
> > > could use one of them as a variable inductor by putting a variable
gap in
> > the
> > > core and then putting the 240V side of both pigs in parallel, not
> > connecting
> > > anything to the 11 kV side of the gapped pig. Does anyone have any
> > > experience of
> > > this, will it work?
> > >
> >
> > Jim Lux wrote:
> > YEs something like this will work... This is how inexpensive welders set
> > the current. They have a core with lots of extra room in the middle
> > (where the windings are. Then, they have a piece of core (the shunt)
> > which slides in and out, changing the leakage inductance, as you turn
> > the handle (which operates a lead screw or other mechanism). When the
> > shunting core is all the way out it is max current, all the way in is
> > minimum.
>
> This does not appear to be quite what I meant, What I had planned was
> to use a
> transformer as a limiter, so I would NOT be connecting the 11 kV winding at
> all -
> in effect it does not exist. In any case due to the way the transformer is
> constructed, it is not possible to place a shunt in the core which would
> cause an
> increase in leakage inductance. Because the windings are wound over one
> another,
> any flux which passes through one coil must also pass through the other, so
> there
> can be no significant leakage inductance when they are operating as a
> transformer.
> I was proposing to only connect the 240V winding and use the transformer
as an
> inductor, with a variable inductance caused by a variable air gap in the
> magnetic
> path.
>
> 240V winding
> ----- ------------------ || -----------
> | | | || |
> M ~~~~~~~~~~~ ~ || ~
> a ---- ----- 240V~ || ~ Coil (11 kV)
> i ---- ----- ~ || ~
> n Variable gap ~ || ~
> s | || |
> ---------------------------------- || -----------
> Transformer 1 Transformer 2
>
> Transformer 1 is being used solely as a variable current limiter and has a
> variable air gap in the core, and transformer 2 as the actual output
> transformer
> and is unmodified. Sorry if I didn't make this clear in my initial posting.
> Does
> anyone have an experience using this arrangement?
>
> --
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