RE: Safety Gap, Grounding, and Secondary Questions/Bipolar Oudin Considerations

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

Original poster: "harvey norris by way of Terry Fritz <twftesla-at-qwest-dot-net>" <harvich-at-yahoo-dot-com>


--- Tesla list <tesla-at-pupman-dot-com> wrote:
> Original poster: "Lau, Gary by way of Terry Fritz
> <twftesla-at-qwest-dot-net>" <Gary.Lau-at-compaq-dot-com>
> 
> Connecting the secondary base to the primary is a
> bad idea on two fronts:
> 1) It's extremely unsafe.  Should you touch a
> streamer or any part of the
> secondary, you'll be exposing yourself to the full
> deadliness of the far
> more dangerous primary-side voltages and currents.

Here is a comment from Leland Andersens forward to R
Hull's CSN commentary, that may give a different view
of the Tesla/Oudin configurations

This is what we do in a normal, classic Tesla coil
with a primary coil tuned to the 1/4-wave frequency of
the resonator which, in this case, is called the
secondary. We can also directly couple energy into the
resonator by injecting it directly into the base of
the coil. This second method is the undisputed, all
time, best way to make a Tesla coil perform!!! The
first method is of lesser value and involves lost and
wasted energy. This is why Tesla abandoned all
experiments with regular classic Tesla coils long
before he ever dreamed of going to Colorado Springs! 

from http://www.tfcbooks-dot-com/mall/more/371tcbg.htm

Here also is a somewhat lengthy way of going around
the barn to circumvent the next objection noted here,
where I have tried to explain, how in my view, the
bipolar Oudin application itself solves the kickback
problems noted as the following;

2) Instead of having a true ground to "push off of",
the secondary base now
has only the primary to work against.  The primary
will ultimately induce
voltage spikes in your AC power lines - the only path
it has to a real
ground.

Gary Lau
MA, USA



Perhaps then the best application of a direct base
excited(by direct line connection as in Oudin Coil)
example is the magnifier, showing indeed that the
direct line base excited coil to be superior to that
of ordinary inductively coupled secondaries.

Also noteworthy of mentioning is the comparison to the
"line tied resonance" method to that conventional
voltage transformation when higher then 60 hz source
frequencies are involved. Recent work with 3 phases of
a 481 hz stator output from a delco remy AC converted
alternator show very problematic issues where the
secondaries (of the voltage transformer intermediary)
appear to add vast amounts of impedance when
attempting to resonate large induction coils of ~ 60
henries. However the line tied method for voltage
input  to these coils yeided little  difficulties
where either delta or Wye configurations of 20 inch
neons could be obtained as simultaneous outputs by
appropriate line tied connections to voltage rises
made by resonance. The difficulties in obtaining
simultaneous neon discharges to be enabled from a
single supply line that feeds two phases, is simlar to
the problem experienced with lighting neons in
parallel, its (just)not common to my knowledge.

I have produced 1.5 cm arc discharges from a needle
arc gap connected between two of these ~ 60 henry
coils that were themselves in bipolar resonance at 60
hz. This shows the ability of large induction coils
when resonated at source frequency to produce voltage
gain. The Q of that system being about 30, enables a
30 fold increase beyond the 440 input to the coils in
parallel from step up transformer. Now what can happen
when this is done is that horrific voltage backfires
can happen with these discharges. I discovered this by
running the coils from variac, where a 2 cm internal
arcing appeared across its isolation transformer
component. To prevent this from occuring, the disharge
was made to instead occur at the transformers
secondaries, as a sort of primitive SAFETY GAP made
from a convention plug with ~ 1 cm clip separation.
What occurs to me in this Oudin connection, is the
idea of making a BIPOLAR OUDIN coil.

Imagine that if the needle arc gap from bipolar
(series) resonant rise that gives voltage backfires
back up the system that originates its voltage rise,
were instead given another Pathway, for the kickback
to travel. That other pathway could represent the line
tied secondaries of bipolar Oudin coils.

The immediate method commonly adapted by coilers to
create the appropriate primaries for such a bipolar
arrangement is to simply have two primaries in series
in the tank circuit, with opposite winding directions
on both primaries and associated secondaries. This may
be the method Bill Wysock uses on his model 12 bipolar
resonator shown at ttr-dot-com.

It may be assumed then that the issue of 180 phasing
of these bipolar resonators has been decided solely on
the basis of winding direction. This being the common
practice, it overlooks a fact and possibility by
assuming that this is the ONLY way to make 180 phased
primaries. In fact it seems to me that a TRUE 180
PHASED TESLA SET OF PRIMARIES HAS NEVER BEEN MADE!

I'm sure lots of folks will protest this statement as
soon as its made, so I will further clarify this in
conjuction with the Bipolar Oudin secondaries
assumption. In order for it to be a TRUE base line fed
resonant voltage rise for EACH SIDE, it (the
respective primaries) must be sourced from a true 180
phased input. Each secondary must be attached on
either side of the primary arc. The primary phasing
conditions to deliver bipolar voltage rises must then
be SOURCED from 180 phased inputs, instead of merely
supplying the imitations made only by winding
direction. This then implies the neccessity for 180
phased banks of capacitors in the (collective) tank
circuits. So a quick preview of bipolar tesla coils I
have noted shows only a single, and not dual capacity
requirement. That is why I think it just has yet be
done to model the idea employed in the (bipolar
resonant)needle arc gap, to a set of 180 phased tesla
primaries for bipolar application.

To return here, the two high induction coils combined
to deliver a q of 30, to create a voltage rise could
have been created two different ways. The initial
consideration to extract the highest Q is to combine
the polarities of both coils in space for magnetic
unison, to increase each coils q by mutual induction.
This could be done also by placing the coils in
series, and series resonating them. The same voltages
present for a needle arc gap could be created in that
circumstance then,but this was not what was done. The
"LINE TIED" approach is literally what would happen if
the arc was made by that technique, and answers the
objections and evident solution to a sensible OUDIN
coil approach.  

In the first example of only using one combination of
series L and C values to resonate at the source
frequency, only a single phased resonance of equal
voltage rise has been accomplished. The line tied high
voltage connection also has only a single point of
origin, and not dual as the "Bipolar" 180 phased
series resonances allow. Thus in the first single
phased example, one end of the needle gap connections
would be the voltage rise at the midpoint of the
series LC combination, and then the other end
connection would have to be either end of the LC
circuit, which of course is connected to the supply
lines, which means that single phased method of
creating a voltage rise for arcing is very destructive
to the input lines, since the high voltage arc beyond
the input voltage is itself striking a supply line
node! This then may be comparable to the general
objection that Oudin coils destructively interact with
the transformer source, and also Terry Fritz'
An Experiment to Investigate Stresses on Neon Sign
Transformers in Tesla Coil Primary Circuits
http://users.better-dot-org/tfritz/site/papers/primarycircuits/pricir.html
quoted here:
There are two popular methods of connecting the
transformer to the primary circuit. The first is to
connect the transformer across the spark gap. The
second method is to connect the transformer across the
primary capacitor. It is generally believed that
connecting the transformer across the spark gap places
less stress on the transformer. This paper will show
the method used to determine that this belief is well
founded. This experiment shows that if the transformer
is connected across the primary capacitor, it will see
much higher voltage and current stresses than if it is
placed across the spark gap. 

Where this ties in is the fact that in the second
undesirable situation, the primary arc has direct
electrical connection to one node of the supply lines,
but yet when both opposite polarity supply lines are
connected on both opposite potentials to primary arc
discharge, the destructive effects are neutralized. We
now also may have to deal with quenching and arc gap
separation to procur firing at zero crossing point,
ect, because these are also the concommitant
associated problems of having a short in parallel to
the supply lines. But here it seems justified to then
state that if a single phased Oudin coil presents such
a noted destructive effect on its AC sourcings, than
employing a bipolar approach for its primaries should
in turn accomplish the same objective. However this is
speculated to allow for an even more remote connection
of the primary arc to its supply lines. In the new
scenario of constructing "true" 180 phased primaries
it becomes possible to construct a 3rd option where
the arc is no longer connected to a node of its supply
lines, and in fact appears with two current limiting
scenarios. Instead of appearing as a short with the
resistance of its arc gap, the bipolar arc gap is
initially current limited by the impedance of two
(inversely phased) LC series quantities in parallel.
In that scenario since the source frequency is far
below the designed primary tank circuit's resonant
frequency, we can open the arc gap all the way open
and know that the  transformers secondaries
consumption is estimated to be only the capacitive
reactance of the circuit (by estimation), especially
since no short appears to those (hv transformer)
secondaries, only the impedance of the primary
capacitive reactances in parallel. Essentially the L
quantities of the primaries can be ruled to be
neglible because the inductive reactance of those at
the source frequency becomes a smaller value with
respect to that of the caps,which act as the current
limiting factor since they are in series on each
parallel branch with the (practically)non current
limited primaries and not much cancelling reactance is
due to the inductive element, (at the input frequency)


Upon closing the arc gap by proximity for firing, once
firing is enabled, a second theoretical current
limiting situation applies. Now we would suppose that
the arc (now)appears as an (estimated) short to the
supply lines initially,after adding the resistance of
the primaries on either side of the arc.  Since the
inductive reactance of the primaries being negligible
at the source frequency, we then suppose that time
period of initial arc formation is then countered by
the formation of the new circumstance of the high
frequency arc itself schematically changing the
circuit to a primary arc gap with tank circuits (at
the resonant frequencies of the dual LC combinations)
on either side of the primary arc gap. The impedance
then of the firing mode becomes 4q times higher after
firing of gap, leading to the speculation that such a
gap would display self quenching attributes.
 
Sincerely 
Harvey D Norris

=====
Binary Resonant System  http://members3.boardhost-dot-com/teslafy/

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