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Re: [TCML] was: How I modified the 3 phase for dual wye 5KV 2xI; Now charge inductor physics.



This page has a good summary of the pro's and con's of gaps in inductors, in particular the trade off between preventing destructive saturation vs reduction in inductance.

http://info.ee.surrey.ac.uk/Workshop/advice/coils/gap/ 

-----Original Message-----
From: Tesla [mailto:tesla-bounces@xxxxxxxxxx] On Behalf Of Jim Mora
Sent: 20 August 2014 08:29
To: 'Tesla Coil Mailing List'
Subject: Re: [TCML] was: How I modified the 3 phase for dual wye 5KV 2xI; Now charge inductor physics.

Hi Bert, Phil,

Not to get too esoteric, but this is of some interest since I am going to try and build a reasonable decent one(s). I understand we want the wire resistance at a minimum, but inductors come in different flavors such as the swinging choke used in older (ancient to some) B+ amplifier supplies. It tends to be a gapped choke to compensate for the DC that is always present.
Standard inductors are not gapped to my knowledge. Some physics forums debate if there is energy stored across the gap. More simply put, would an inductor sized not to saturate at the extreme current peaks or a gapped inductor (both assuming low DC ohms) be the more ideal charge inductor?
Indirectly we are entering the gap debate I suppose. I see it as the energy stored in the magnetic field which a gap would tend to decrease? I suppose it comes down to a compromise. I'm curious how those radar inductors are designed in this sense. Yours is a beast!

Jim Mora

-----Original Message-----
From: Tesla [mailto:tesla-bounces@xxxxxxxxxx] On Behalf Of Bert Hickman
Sent: Tuesday, August 19, 2014 8:20 PM
To: Tesla Coil Mailing List
Subject: Re: [TCML] How I modified the 3 phase for dual wye 5KV 2xI

Hi Phil and all,

Phil wrote:
> (I've jumped around a bit too different emails here, hope you can 
> follow)
>
> Bert's figures in this vary from what Richie's figures give. Now I 
> know
that
> assumes the calculator faithfully reproduces Richie's formulas, but 
> I'm certain after a lot of testing it does, so who's right, Richie or Burt?
> I realise the smoothing cap will vary with 3 phase AC admittedly, but
after
> it's rectified it's all DC regardless, so the inductor and tank cap I
would
> consider to be the same as for our single phase AC input.

The biggest difference between Richie's model and the spreadsheet calculator is that I use a lossy charging circuit model that takes into account charging inductor losses. <snip>

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