Re: NST Rework?

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

Original poster: "David Sharpe by way of Terry Fritz <twftesla-at-qwest-dot-net>" <sccr4us-at-erols-dot-com>

Nolan

Unwinding the primary turns to raise turn ratio will in theory work, but
in practice, you need a specific number of primary turns based on
power throughput, and applied primary voltage.  If you cut the number of
primary turns, the primary current will rise significantly, you will run a good
risk of burning out the primary, and your power capability of the NST
will be severely limited.

Further, check archives for transformer design equations, build a magnetic
model using equations in a spreadsheet, and watch what happens to primary
load current as you reduce primary turns and try to maintain same power
throughput.  As a first order model, as you cut number of turns in an inductor
in half, inductance is reduced by a factor of 4, which will increase current
in primary by a factor of 4 (by holding input voltage constant).  This suggests
a 16X i^2r heating increase in primary winding heating (holding load power
constant), versus powering with original winding at nominal voltage input.
In short, not a good idea...

Regards
Dave Sharpe, TCBOR
Chesterfield, VA. USA

Tesla list wrote:

> Original poster: "Nolan Moore by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<moonol05-at-email.pct.edu>
>
> Hi all,
>
>     I was thinking about taking a 7500V -at- 60ma franceformer that I have and
> doing a little rework on it.  The transformer is already depotted and clean.
> What I was thinking about doing is removing 1/2 of the primary windings to
> produce 15kv -at- 60ma.  Is this a good idea to do and will it work? Will there
> any problems if not or if only minor ones, I think I may go for it. Thanks!
>
> Sincerely,
> Nolan Moore