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Re: Current Limiting and Impedence

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

On 8 May 2005, at 8:41, Tesla list wrote:

> Original poster: "Paul B. Brodie" <pbbrodie@xxxxxxxxxxxxx>
>
> Gerry,
> I'm really interested in what you guys have had to say on this thread.
> Please let us know the results of your investigations into gapless
> toroids. I do have one little question: are there gapped toroids? I've
> never seen one and it seems that would defeat the purpose of using the
> toroid shape in the first place. Regards. Paul Think Positive

Some toroidal cores have a distributed airgap, namely iron-powder
types. These are designed to handle high DC currents and are totally
unsuitable for use as transformer cores and large alternating
currents.
     Gapping a core artificially boosts the length of the magnetic
path enormously.

Malcolm

>
> ----- Original Message -----
> From: "Tesla list" <<mailto:tesla@xxxxxxxxxx>tesla@xxxxxxxxxx>
> To: <<mailto:tesla@xxxxxxxxxx>tesla@xxxxxxxxxx>
> Sent: Sunday, May 08, 2005 2:09 AM
> Subject: Re: Current Limiting and Impedence
>
> > Original poster: "Gerald Reynolds"
> <<mailto:gerryreynolds@xxxxxxxxxxxxx>gerryreynolds@xxxxxxxxxxxxx>
> >
> > I'll reply to my own reply.
> >
> > Maybe what I'm missing is: if I increase the area to prevent
> saturation, > the inductance goes back up so maybe this is self
> defeating. I think it is > time to play with some real numbers with
> gapless toroids and see what the > inductance and saturatiion levels
> are. > > Gerry R > > >>Original poster: "Gerald Reynolds"
> <<mailto:gerryreynolds@xxxxxxxxxxxxx>gerryreynolds@xxxxxxxxxxxxx>
> >>
> >>I wonder if the real issue is physical size between the two
> designs. If I >>take a gapped ballast and remove the gap, the
> inductance goes up. I will >>need to reduce the number of turns to
> get back to the original inductance. >>This will increase the volts
> per turn that will push the ballast closer to >>saturation unless I
> increase the cross sectional area. > > > >
>
>
>