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Re: Guide 60HzMatch

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> 
> Subscriber: tom_mcgahee-at-sigmais-dot-com Tue Jan 28 22:58:51 1997
> Date: Tue, 28 Jan 1997 15:40:47 -0500
> From: Thomas McGahee <tom_mcgahee-at-sigmais-dot-com>
> To: Tesla List <tesla-at-pupman-dot-com>
> Subject: Guide 60HzMatch
> Critique style, tone, syntax, grammar, but especially home in on content,
> useability, etc. For all I know, this may be totally wrong.
> If you have ANY relevant material, please e-mail to me Re:Guide
60HzMatch.

Tom-

> The transformer secondary winding has a characteristic impedance at
50/60Hz
> that will limit the maximum current that the transformer can deliver. You
> can model the transformer as a perfect voltage source in series with an
> inductor and a resistor. The resistance is caused by
> the length and diameter of wire used in the construction of the
> transformer's secondary. The inductor represents the inductance of the
> transformer secondary, which causes its AC resistance at 50/60Hz. {Fig ??
> Eq ??}

I would have thought that the inductance in series with the resistor and
voltage source would be indicative of the transformers "leakage" inductance
-not- the
whole secondary inductance:  if a transformer with perfect coupling and
zero
resistance was connected to a perfect ac voltage source on the primary side
the secondary's output impedance would be zero.

> 
> Note: Do not confuse this 50/60Hz resonant frequency with the resonant
> frequency of the RF portion of the Tank circuit, or the self-resonant
> frequency of the secondary. 
> 
> 
> Additional Remarks:
> 
> If RF chokes are introduced into the transformer circuit, then their
> inductive reactance at 50/60Hz may have some effect on the total
inductive
> reactance, though it is generally small compared to the inductive
reactance
> of the transformer's secondary. 
> 
> The RF impedance of chokes does not enter into this
> discussion of matching, because in matching we are only concerned with
the
> charge cycle, not the discharge cycle. 

Well, OK but I think it's worth mentioning that power/neon transformers all
have
rather complicated behavior as a function of the frequency applied. The
seconday's
impedance generally goes down rather significanly (1-2kOhm ) near the tesla
resonant frequency even though the secondary inductance is some number of
Henries. The coupling between the primary and secondary is also a strong
function of frequency and is almost neglible for telsa resonant
frequencies.

It would also be nice to include formulas (fairly common) for estimating
transformer
parameters like: maximum primary voltage allowed before core saturation,
typical
silicon steel permeability, and maybe the concept of reluctance.

-Ed Harris