Re: OLTC - Split core inductors

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Jim Lux by way of Terry Fritz <twftesla-at-qwest-dot-net>" <jimlux-at-earthlink-dot-net>

Look at those tape wound air core inductors, remarkably high inductance in a
fairly inexpensive small package.. and, I'll bet that a simple core might
jack the inductance up pretty high.

----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Friday, August 16, 2002 4:22 PM
Subject: OLTC - Split core inductors


> Original poster: "Terry Fritz" <twftesla-at-qwest-dot-net>
>
> Hi All,
>
> I have been learning a whole lot more about inductors than I ever wanted
to
> know :-p
>
> A closed iron inductor that can take about 5 amps, 120Hz, 150mH, and 3
ohms
> DC resistance would be very large due to saturation (also has those odd
> non-linearities).  The inductor should not be over 3 ohms of DC resistance
> since it hurts the resonant charging (5 amps at 3 ohms is also 75 watts!):
>
> http://hot-streamer-dot-com/temp/OLTC08-16-05.gif
>
> So I looked at air core inductors using the information at this nice site:
>
> http://www.ee.surrey.ac.uk/Workshop/advice/coils/air_coils.html
>
> I did a lot of math and Excel stuff and came up with this list of
> "possibilities":
>
> http://hot-streamer-dot-com/temp/OLTC08-16-06.gif
>
> It is based off the needed inductance, resistance, and wire data.
>
> There are no practical solutions!!  For example a #12 wire coil 13.5
inches
> in diameter with 2300 feet of wire at 60 pounds!!
>
> The spreadsheet is here if anyone cares:
>
> http://hot-streamer-dot-com/temp/airwire%20chart.xls
>
> So we are looking at a big split core inductor like my split variac core:
>
> http://hot-streamer-dot-com/temp/OLTC8150009.jpg
>
> It measures 47mH so I need SQRT(150/47) = 1.79 as many turns on it.  Very
> possible...  It is only 0.4 ohms DC resistance right now and it has
> excellent V/I and inductor characteristics.  I am sure a MOT core or any
> big iron core be used too.  Sad, we need iron, but the H*** with it ;-))
> It really only weighs 3 pounds 14 onces...  More research later will be
> need into these inductors and figuring out how to make them easy for
anyone
> to reproduce.  Now I know why my request for ideas on inductors went
> unanswered ;-))  I ain't easy...
>
> I also got the caps today from Richardson electronics.  Took three weeks
> and I didn't know if they were ever really going to come, but they did.
> Chris was also getting caps for me :-|  No worries, I think we can find a
> use for them in the higher power version :-))
>
> Much construction work to do...
>
> Cheers,
>
> Terry
>
>
>
>
>
>
>