Re: Charging inductors for resonant charging

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

Original poster: Esondrmn-at-aol-dot-com 

In a message dated 1/30/04 11:13:29 AM Pacific Standard Time, 
tesla-at-pupman-dot-com writes:

- snip -

I repair electric golf car chargers.  The old ones have big massive 
transformers in them.  The old chargers weigh 30 to 40 pounds, most of 
which is the transformer.  I have often thought they would make great cores 
for a project like this.  Go to your local golf car sales companies and ask 
them if they have any old chargers they want to get rid of.

Ed Sonderman

>     Large inductors; maybe someone here can help.  I have one or two
>charging chokes used for a 250 watt average power radar modulator and
>they're about as big as an MOT.  I don't remember the ratings but have
>saved them for many years with the idea of using them in a resonant
>charging circuit for a "DC TC".  I have a 7500 volt 60 Hz power
>transformer out of an old Navy radar and intended to rectify it and use
>resonant charging along with an RSG.  Like many other projects it has
>yet to get off the ground.
>
>     Maybe I've misinterpreted what you wrote.  I'm used to thinking in
>terms of average DC current, peak operating voltage, and frequency.  I
>just dug out "Volume 5" (Glascoe and Lebacqz) and in Figure 9-13, page
>375, they show samples of various DC charging inductors.  The biggest
>one in the picture is rated at 0.4 amps, 17 kV peak, and has an
>inductance of 19 henries; it weighs 71-1/2 pounds and is potted in a can
>which looks like about a 7" cube.  You seem to want something over twice
>as big.  There's a whole chapter of the book devoted to "charging
>circuits for line-type pulsers" of which I'd say a TC is a degenerate
>case.  There is some information on "THE DESIGN OF D-C CHARGING
>REACTORS".  Almost the first sentence reads "Reactor design is usually
>based on experience.  However, in the absence of suitable previous
>experiende the design process can be started mathematically."  Design
>equations and discussion follow, which don't look too horrid.  About
>four pages of stuff which I could copy and send you if you're
>interested.  I notice that the magnetic units are ampere turns/in (not
>so bad) and flux is expressed in "lines" (lines/square inch).  The work
>described was started about 1942, the same year I started in engineering
>school, and apparently the authors had studied the same system of units
>as some of my instructors.  We had so many different systems of units
>(english, cgs, MKS, MKS rationalized, etc.) thrown at us that I've been
>perpetually confused.
>
>     I suspect your reactor could be wound on the core of a transformer
>weighing of the order of 100 pounds or so, and if memory serves me right
>small pole pigs fit into that class.  Someone who owns some might
>correct me.  In the "good old days", here in the Los Angeles are it was
>possible to go to the Edison Company salvage yard in Alhambra and pick
>up small (unpotted) pole pigs for free.  2200 volt to 110 volt units
>were good for plate transformers for ham transmitters and I suspect
>there are some of them still around.
>
>Ed