Re: Rebuilding an OBIT

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

Original poster: "Finn Hammer by way of Terry Fritz <twftesla-at-uswest-dot-net>" <f-hammer-at-post5.tele.dk>



Tesla list wrote:
> 
> Original poster: "Jochen Kronjaeger by way of Terry Fritz
<twftesla-at-uswest-dot-net>" <Kronjaeg-at-Stud-Mailer.Uni-Marburg.DE>
> 
> >
> > TRANSFORMERS DO NOT SATURATE DUE TO TOO MUCH CURRENT BEING DRAWN !
> >
> 
> Then how come that you need bigger cores for higer power?

Jochen, Richie, all!

Interesting question, which has kept me pondering for years.

I think the answer is this: you don`t _need_ a bigger core for higher
power, but ultimately it helps.
To cut down the power loss in the copper, the wire has to increase in
area when the current goes up. This could be solved by making the
winding window in the (still small) core bigger. However, you would
still need a lot of turns per volt.
If the core crossection is made bigger, the induction per turn is
increased, so that fewer turns are needed, therefore there is better
space to use thick wire.

So the recommended power troughput of a given core size is a compromize
btwn. copper losses and iron losses.

Somehow it is my feeling that the core is only needed to make the
transformer able to stand idle, open circuit secondary, without drawing
excessive current. If the windings were properly interleaved, and the
leakage inductance was extremely low, it would possibly be able to run
at full load without the core.

Since this is the case with a tesla coil transformer started at full
power from a contactor, it would make an interesting experiment, however
making those interleaved coils for a high voltage stepup transformer
poses an interesting insulation challenge.

Cheers, Finn Hammer

snip