Re: OLTC - Split core inductors

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

Original poster: "Bert Pool by way of Terry Fritz <twftesla-at-qwest-dot-net>" <txsharpie-at-prodigy-dot-net>

Terry,
You might want to look at using a "metglass" core.  This stuff makes for 
incredible inductor cores, and is much more readily available than just a 
few years ago.  This might allow the design of a more reasonable size 
inductor with the saturation characteristics you need.
Bert Pool



At 05:22 PM 8/16/02 -0600, you wrote:
>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
>
>
>
>
>