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Re: Math help...



Original poster: "Ed Phillips by way of Terry Fritz <twftesla-at-qwest-dot-net>" <evp-at-pacbell-dot-net>

> Ed -
> 
> My understanding is that with electric circuits currents flow in conductors
> and resistance (ohms) create the losses. With magnetic circuits flux flows
> in steel because of electromotive force and there are no flux losses. Eddy
> currents flow in conductors and are electric circuit resistive losses.
> Hysteresis is another matter but not involved with Tesla coils. Is this
> incorrect?
> 
> John Couture
> 
> ---------------------------

John:

	Reading my mail a couple of days late so someone else may already have
commented on this.  What you mean by the term "flux losses"?  I'm not
sure of your question or statement there.  Not all of the magnetomotive
"force" generated by a coil in an iron-cored circuit is linked with the
core; a small amount "leaks" into the surrounding space.  This doesn't
necessarily imply any loss of power, however.  Hysteresis loss results
from the fact that some work must be done to reverse the direction of
the magnetic field in the ferromagnetic core; this is a characteristic
of the particular core material and flux density, and is independent of
any eddy current losses.  In the RF circuits of a TC there is a lot of
flux "leakage".  That is to say, by no means all of the magnetic flux
generated by currents flowing in the primary links with the turns of the
secondary.  However, that doesn't necessarily produce any power loss or
reduce the efficiency of power transfer from primary to secondary.  The
losses are still pprimarily the ohmic (i^2R) losses in the resistance of
the primary gap and the wire in the primary and secondary.  Losses in
the self-capacitance of the secondary are probably negligible, but I'm
not sure of that.  Certainly they are tiny compared to the power going
into the streamers.

	There are small power losses which could result from radiation from the
primary or secondary (for devices with typical TC dimensions these
almost zero at the frequencies at which we work), or eddy current losses
if some conductive material is in the field of the primary.  I suspect
these are always negligiblr.

	This answer looks clear as mud to me.  Perhaps Antonio can state it
more clearly.

Ed