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Re: Elementary Lecture



"   Why sparks will leap between the toroid and a grounded object is
quite
understandable; but the magic of a Tesla coil is that sparks
spontaneously
branch
out into thin air, connecting with seemingly nothing.
   Consider 2 devices: A million volt Tesla Coil, and a million volt 60
Hz
transformer. The TC will emit a discharge into the air that connects to
nothing.
We'll help the million volt xfmr by grounding one of the secondary HV
terminals.
Do sparks spontaneously emanate from the other HV terminal into thin
air? No.
   I certainly have not read all available Tesla coil theory, but I've
yet
to see
a thorough explanation of why a Tesla Coil does what no other device can
do--emit
sparks that terminate in the air.
Dave Hartwick"

	At the frequency of a Tesla coil there is no time for the air to
deionize between cycles of the RF (during a single discharge of the
primary circuit), while with the 60 cycle power transformer there
certainly is.  Once the ionization trails form in the air, they stick
around from spark to spark.  You can certainly get corona off the HV
terminal of your transformer, and if you put a metallic object at the
end of a (very well insulated) pole you can draw long arcs.  I saw a
demo once by an operator at the Big Creek plant of Southern California
Edison.  He had such a pole, with a hook on the end for pulling HV
switches.  He stood directly under the main 220 kV lines running out of
the station, put the hook against one, and was able to draw arcs at
least 12" long as he pulled it away.  Scared the pants off me!  I would
think that if the wooden pole were just a little bit damp or dirty,
there would be a big flash and burned up operator!

Ed