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Re: hv connections
I was tought incorrectly. My mentor (a list member who I won't embarress)
vehemently taught us that under normal conditions (like not living in a 90%
salw water atmosphere) that apprx 600VAC was the bare minimum voltage for
the breakdown of air. I looked at the wire we use and almost all of it is
rated at 600VAC so this made perfect sense. Could someone tell me the
paramiters and such for minimum voltage breakdown of air? Other
dialecterics? I want to make sure I fill these holes im my (and those around
me) knowledge before I start blowing holes in my hands. :) I'm terribly
allergic to pain. And given that Jim works for NASA I would have to assume
he knows a fair bit more than my mentor. :)
>Original Poster: "Jim Lux" <jimlux-at-jpl.nasa.gov>
>
>Comments interspersed below..
>
> > Original Poster: "Christopher Boden" <chrisboden-at-hotmail-dot-com>
> > >Original Poster: Fucian-at-aol-dot-com
> > >what is the proper material for connecting a coil.like nst connections
>and
> > >so on.i want to completely knock out any possibility for danger.
> > >
> > >
> > For NST interconnects (to paralell NST's) I use Neon Sign wire, it's
>VERY
>
> > thick insulation and rated for 15,000Volts. I still don't trust it
>though.
> > Only once have I held one while hot, that was at a neon shop and
>everyone
>
> > was looking at me like I was a wus when I would VERY gently hold the
>wire.
> > These guys do it everyday and have lost their fear and respect for the
>power
> > involved.
> > I only use it for NST interconnects because it's small, only 14AWG.
>
>14 AWG will easily carry 20 amps, although it's RF impedance might be
>higher, but at the relatively low frequencies of a TC, it's just not going
>to make that much of a difference.
>
>Either you believe the ratings or you don't. At some point you've got to
>believe in your design. Of course, this is why I like coax with the shield
>grounded. even if the insulation breaks down, its going to spark to
>ground, not my hand.
>
Good idea :) Is it safe and reliable?
>The voltages in a TC primary might also be somewhat above the voltage of
>the NST...
>
>
>
>
> >
> > Unless it specifically says so on the wire, almost ALL wire is rated for
>600
> > Volts.
>
>Actually, that would be 300V.. most PVC insulated hookup wire, for
>instance, is rated at 300V.
>
All the wire around here, if it's labeled at all, is rated for 600VAC with
rare exception. Maybe I just buy weird wire or something...hmmmm The little
hookup wire we have I'm sure is rated much less. And I have yet to ever use
600VAC for anything.
> The reason for this magical number is that's the definition of High
> > Voltage. At about 600 Volts electricity will arc through air, below that
>you
> > can have 2 wires with only thousandths of an inch apart and as long as
>they
> > don't touch it will not arc. Though keep in mind this is only true as
>long
> > as they don't touch.
>
>Legally (electrical code, wise), low voltage is <50Volts.
For us it's anything under 120V
>Actually, the minimum sparking voltage for air is around 250 Volts. BUT,
>and this is a big proviso, if there is anything (e.g. insulation, solids,
>liquids, etc.) between, the sparking voltage can be much smaller.
>
>
>
Teach me more about this, Please.
Thank's for the knowledge upgrades guys :) Some of these things we get
taught and never test for ourselves, we have to accept them as gospel from a
person we can trust. Sometimes the teacher is wrong for various reasons. I
need to make sure what I learn is correct for a safety standpoint, and
because I teach it to others and have a responsibility to my guys. I want to
clear up all the old tesla myths and such BEFORE I teach it to another
person.
Remember, how many of you asked your teacher why the sky was blue. How many
still believe that it's a reflection of the ocean? A simple answer, that to
them makes sense, though wrong, has been handed down for generations.
Thank's guys :)
Chris "Still Learning, but getting there" Boden
The Geek Group
www.geekgroup-dot-org
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