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NST Power Factor Correction -at- 476 hz/Ohio Teslathon Plannings

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

Hi all tesla coilers, once again this is harvich, host
of last years Ohio Teslathon. My knowledge of tesla
coils is somewhat limited, but I like to try some
unusual things with unconventional components, such as
high induction coils. I had also posted some past
stuff on the possibilities of running tesla coils from
an AC converted car alternator.

Concerning this subject in general which has to do
with 3 phases, and an increased frequency input now
placed by a wider pulley arrangement to deliver 476 hz
has been assembled. A somewhat satisfactory
demonstration of the resonant voltage rise on 60 henry
coils has been made, where simultaneous discharges of
20 inch neons in either delta of wye configuration has
been made(between the phases from voltage rise
midpoints between L and C) These use ~2 nf aluminum
foil/plexiglass capacities. However these bulb firings
show potential problems in trying to make a 3 phase
tesla coil system. The way the power input on this
system is regulated is by AC variac control to a 4/1
stepdown transformer and then rectification by diodes
and capacitive filter to deliver a filtered DC to the
alternators field rotor. What happens is that the
three bulbs do not easily share these interphasal
currents. At a lower variac input of  18 to 20 volts
the bulbs may share the discharge equally, but when
the variac is turned up, one or even two of the bulbs
may become extinguished, and the remaining bulb(s)
become the predominant current path shown by increase
of illumination. Thus it may be the fact that for a 3
phase tesla coil application it may be better to only
run two coils, combining two of the phases in series
for one coil, and the remaining phase as its bipolar
opposite. The reasoning behing this adaptation is that
if the neons model what will occur as high frequency
disharges, then the two more closely tuned coils might
hog up all the arcing potential, leaving out the third
coil as ineffective.  A bipolar adaptation eliminates
that problem. But before going more off topic here let
me mention the real problem and reason for making this
post. In earlier experimentation producing 188 hz, the
variac was set at 70 volts for standard field
operation, which produced ~ 19 volts on the stator
outputs. The increase of voltage beyond that point
would be going beyond recomended operation limits, but
there was only small voltage losses (probably
saturation of field rotor) incurred by increasing the
field amperage. Now we are always tending to worry
about saturating the field coil, and we never think
about the other possibility, where the stator itself
due to the volume of currents being asked for then
instead saturates. Can someone comment whether this is
possible? As one will understand, at 476 hz the field
rotor is rotating faster than 188 hz, so the amount of
field amperage inputed is reduced to obtain the same
19 volts stator output, which is then achieved at ~ 20
volts variac input. What happens is that the resonant
voltage rise in this case becomes very non linear.
There are actually two stages of voltage rises,to get
the neons to discharge across the 60 henry coil
resonances: where the first stage is made as 12.5 ohm
inductances of .15 Henry coil system where this
voltage rise can be measured by meter. This is made by
a collection of 30 14 gauge 500 ft wire spools, where
10 of the coils/phase are used. This is what gives a
preliminary voltage rise to the high induction coils,
which then gives another voltage rise to light the
neons. Now the variac can be increased to about 40
volts where something very funny begins to happen. The
first monitored voltage rise will climb to about 440-
480 volts, but then the variac being increased to 50
volts will show a BIG voltage drop across the entire
system, where the voltage rise on the first delta
series resonance is shown to go down to 100 volts.
Since the former conditions at 188 hz involved a 70
volt variac input, with  little or no saturation
effects, I conclude that it cannot be the field
saturating, but only the stator. So here the limits of
the alternator to produce amperage are being
encountered, as when the output is asked for it will
only supply so much before everything begins to shut
down. So this is where the crucial importance of power
factor correction may come into play at 476 hz.

Since the alternator apparently will only deliver so
much power, that power must then be inputed in the
correct fashion by power factor correction to each of
3 NSTs in place of the 60 henry coils. As one can
easily speculate, since the frequency is much higher,
the importance of power factor correction becomes much
more relevant since the reactance is much higher at
this higher frequency.

So here is where I can take suggestions. This is the
approach I think that should be used. First the NST's
should be arranged in unloaded secondary condition
directly across the delta alternator outputs, and the
reactive current measurements made. Then this should
be repeated with the NST's secondaries shorted. This
should give two different figures of inductive
reactance amperage consumption. My question then
becomes which inductive reactance figure should be
used for power factor correction? I would imagine that
a capacitive reactance closer to the shorted condition
would be the correct approach. Once this capacity is
determined it can be put in series with the NST's as
inner delta series resonance, bisecting the outer 14
gauge delta series resonances, as was done with the 60
henry coils. Now the first objection I would expect to
be heard is that the power factor correction
capacitance should be in parallel and not series. This
may turn out to be true however some complications

These complications involve the fact that the
alternator will only put out about 30-40 volts maximum
before this saturation effect takes place. The NSTs
can take 120 volts, so a preliminary voltage rise
before inputing voltage to the NST's are needed. A
10/1  step up 3 phase delta to delta transformer is
available for that duty. However in that situation the
transformer inputs themselves would have to be power
factor corrected. Now essentially the .15 Henry 14
gauge delta series resonances are already power factor
corrected when the condition of a trisectional short
is made. That is because making this short turns the 3
series resonances into 3 tank circuits.  But again for
the sake of comparisons both the series and tank
connections can be tried, and the voltage inputs to
the NST noted for comparison. We can actually consider
these 14 gauge 12 ohm inductors as ballasting for an
application where the transformer is not current
limited. For the Ohio Teslathon I am in the process of
aquiring such a 15,000 volt pole pig, as I won the
Ebay bid for the  Victory neon bombarder transformer.
I would assume this can be used as is for tesla coils
driven by an alternator,again with power factor
correction so if anyone wishes to try this at the
convention, it will be available.

Now to end this long post, I would wish the attendees
to be notified that the Ohio Teslathon is being slated
for a  July Saturday. I enjoyed all of your company
last year, so Y'all are invited for a reunion. Marc
Metlica had mentioned he was interested in also
promoting one at his place, but I am going ahead and
scheduling this one, and the more events the merrier. 
A really ideal event may be in the works for August
where the Portage County Ham Fest Occurs. I will try
to get the President of that Association to attend
this event, and give an opinion whether coilers could
gather at his very well organized ham fest to show
some arcs to folks/ and promote public interest in
tesla coils. They rent tables under tents there and
many years ago I tried a demonstration of a copper
magnetic motor there and they didnt charge for the
table, so maybe a free deal could be in the making, as
he could advertise tesla coils in his event.
But in any case the folks can drop me a note offlist
if they are planning to attend this years event.

Some of the interesting research involving 60 Henry
coils will also be shown at this event. Last year I
was unable to demonstrate that the secondary of a
tesla coil could be scoped out for resonant frequency
by merely having a plate area  extended from a single
gap series connection to the large induction coils 60
hz resonant voltage rise, where that plate area can
spatially induce both conventional and longitudinal em
voltages to an oscilloscope measuring the voltage
induced directly on the inductor. This arc gap method
has now been superceeded by use of a small neon in
place of the arc gap, so I would like to try this
again where the neon is directly plate attached as a
polar capacity. The high induction system is also set
up for demonstration of a variac regulated 1.5 cm
needle arc gap as bottom linked as electrical kickback
video on 
homepage at

Some individual jpegs of these unusual kickback
discharges can be found in the files section of 

Also concurrent work on interaction with magnets as hf
emmittors as shown on
will be shown and the ideal application to high
frequency agriculture also shown. This device produces
prodigious ozone although no arc takes place. The high
frequency input will accomplish both electrical
stimulation of plant life and simultaneous ozonation
of its water supply. In earlier applications of plants
being stimulated by the magnet stimulated induced rf
the plants actually moved in electrostatic attraction
to a persons fingers within 1/2 cm. This delivered a
mild high frequency skin effect shock, not as direct
as the series gap shock Marc accidentally got last
year, when I accidentally walked off leaving him
holding the  polar capacity plate piece(Sorry about
that Marc)

Also if anyone specifically requests, I can
demonstrate how the neon bulbs can be made to become
very efficient EM emittors, where an NST does not
accomplish that aspect as well, as it is a
ferromagnetic voltage supply versus that of a resonant

I think thats all the time for now, as I have snuck in
enough off topic stuff in this posting. I welcome the
more theoretical posting of files to 

When time permits I will be adding Mike Hollisters
Inductance Max file there. I am looking for standard 
and bipolar tesla coil schematics, and magnifier
schematics if anyone would care to post them there.
Also all theoretical files concerning skin effect,
Medhurst H/D ratios, power factor correction ect are

Also a list exists on e groups where I will update and
post there concerning the concurrent alternator work,
as it is rather off topic at this time for  tesla
coils in general.

Sincerely HDN

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

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