Re: Tesla Coil RF Transmitter <AC Neutral>

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Sparktron01@xxxxxxxxxxx 

Dan

(Terry: OT shield UP)

I must disagree with your contention about neutral not being a 60Hz AC
return path.  With single phase AC power, neutral is the "grounded
conductor" (current return path), and the ground bond (bare or green wire)
the "grounding conductor"  (Definitions courtesy of National Electric Code).

The neutral current in a _balanced_ three phase feeder (Y connection 
assumed) will tend to zero with a balanced load, however, if there 
are any odd order harmonics, the triplen frequency currents will 
vectorially ADD.
There have several cases in the literature of data processing centers
catching fire due to overloaded three phase neutrals from harmonic
current content.

I am aware of one case in a manufacturing location I supported; that a
120-208Y lighting feeder nearly caught fire, due to harmonic content from
florescent lighting on the entire floor of the factory.  Aluminum conduit
was at least 140 deg F (caused minor 1st degree burn to a unsuspecting
employee).

(OT shield DOWN)   :^)

Regards
Dave Sharpe, TCBOR/HEAS
Chesterfield, VA. USA


> Original poster: "Dan" <DUllfig@xxxxxxxxxxxxx>
>
> Your contention that the current needs a two way path is, i believe,
> incorrect. That would be true for DC currents, but not AC. When the
> current is flowing from the tramsmitter to the receiver, the charge
> accumulates in the top capacitance of the receiver. When the current
> is flowing back, it flows back out of the reciver's capacitance, into
> the transmitters capacitance.
>
> It is analogous to a hydraulic system, where instead of pumping the
> oil always in one direction (you need two hoses to do this), you kept
> pumping the oil back and forth. When you do that, you don't need a
> return hose, because the oil can go into an accumulator at each end.
> Think about it.
>
> Dan
>
> PS.: in common household AC, the neutral is not really a return path
> either, but a terminal to collect all three phases and add them
> together. By definition, being neutral, the neutral does not carry
> any current (beyond the untility pole, that is).
>
>
> ----- Original Message -----
> From: <mailto:tesla@xxxxxxxxxx>Tesla list
> To: <mailto:tesla@xxxxxxxxxx>tesla@xxxxxxxxxx
> Sent: Sunday, September 11, 2005 8:31 PM
> Subject: Re: Tesla Coil RF Transmitter
>
> Original poster: Ed Phillips <<mailto:evp@xxxxxxxxxxx>evp@xxxxxxxxxxx>
>
> "Hi all, this response isn't directed at any one in particular; I just
> have a few observations:
>
> 1 -- the earth is conductive, or we would not be grounding equipment in
> it;
> 2 -- RF can be conducted thru a conductor, or coax would not exist.
>
> and finally,
>
> 3 -- given the above statements, why is it so hard for anyone to
> believe that Tesla was transmitting by conduction through the earth,
> and not propagation through the air?! Just becuase you CAN transmit
> RF through the air, doesn't mean it is the ONLY way to do it."
>
> It is impossible to believe that transmission was solely through the
> earth, as many seem to believe.  Take your example of a coax cable.  The
> current flow is through the center conductor with a return path through
> the inside of the outer conductor.  TWO-way circuit!!!  In Tesla's case,
> at least as we interpret it now, the current was to flow into the earth
> from the bottom of the coil.  Period.  No return path.  No way at all
> this could work.  I wonder if Tesla is being misinterpreted and never
> intended to say that there was no return path for the current carried
> through the earth.  For sure his patents talk of a TWO conductor
> transmission path, with one conductor being the ionized "upper layer"
> and the other being the ground.  Always TWO conductors.  Just read the
> patents.  When he speaks of "driving currents into the ground" that may
> just be hyperbole.
>
> "And Sam, you said the TC transmits poorly; considering that Tesla was
> lighting up light bulbs with his receivers, seems his coils were
> transmitting just fine..."
>
> No foundation for that statement.  He did indeed light bulbs, probably
> through inductive or capacitive coupling (unless you believe the stuff
> about lighting many bulbs many miles a way, a statement with no proof at
> all and apparently invented after his time).  However, he never even
> mentioned how much power was transmitted or being wasted.  Probably most
> of it was wasted.  Efficiency was probably nil.
>
> "Some of his earlier experiments involved running a loop of cable
> around his laboratory. He would run RF through it, and light up
> special bulbs anywhere in his lab. He was constantly running
> experiments, probably hundreds of them by the time he was through. If
> his transmitters acutally needed an Aerial, don't you think he would
> have figured that out? why would he drop the earlier aerial (say that
> really quick three times :) in favor of a capacitive top load, if it
> performed worse? It's not like he never tried an antenna!"
>
> That was simple inductive coupling and not transmission.  No mystery,
> no miracle, no significant technical accomplishment except for the high
> frequency involved and his method of generating it.  You can do it just
> as well as he did and the results will be just as good.
>
> Ed
>
>
>
>
>