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Re: [TCML] Isolated secondary building up charge



Excellent information! Thanks to everyone who responded.  Now that my coil is finished I need to document it and get some good pictures of everything (as well as upload those I've already taken)

If anyone is in the Las Vegas area, I will be showing off the coil as well as the coil winder at the Las Vegas Mini Maker Faire on April 5th.  Still trying to figure out if I'll actually be able to run the coil.  It's looking doubtful since the building are all trailers with low ceilings, and anything outside is going to be during the day in the sun.  Adequate grounding is also something I doubt would be possible.

perl -e 's==UBER?=+y[:-o]}(;->\n{q-yp-y+k}?print:??;-p#)'

Bert Hickman <bert@xxxxxxxxxxxxxxxxxxxxx> wrote:

Hi Krux,

Getting "zapped" by a charged secondary is a kind of a rite of passage 
for coilers - you are now a more experienced coiler..  :^)

This phenomenon is thought to occur when secondaries that are coated 
with a dielectric layer retain electrostatic charges on the outer 
surface. The charged dielectric becomes a type of "electret" - the 
electrostatic mirror of a magnet. Charges become deposited on the 
coating surface during coil operation via corona charging or through 
small racing sparks. Typical coatings, such as multiple layers of 
polyurethane, or two-part coatings of polyester or epoxy, are excellent 
electrical insulators, so any deposited charge becomes temporarily 
stranded. One deposited, they'll remain trapped for days or even weeks 
afterward. Their presence also makes your secondary a magnet for any 
airborne dust. You can sometimes feel their presence when they lift the 
hairs on the back of your hand as you bring it near the top portion of 
your secondary. You may even feel and hear small snapping sparks as you 
discharge regions of the coating.

When you touch or carry your secondary coil, some of these stranded 
charges transfer to your hand, and you become one plate of a charged HV 
capacitor - the secondary winding is the other plate. If you then get 
too close to the top or bottom terminal of your winding, you'll 
discharge this capacitor, sparking it to your nose or forehead, or to 
lower parts of your body from the base of the coil. The capacitor 
discharge can be quite painful for larger coils, and it has caused some 
coiler to drop and damage their secondaries. You can avoid getting 
zapped by connecting yourself to the secondary winding with a small clip 
lead before moving it.

Best wishes,

Bert
-- 
Bert Hickman
Stoneridge Engineering
http://www.capturedlightning.com
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Krux wrote:
> So this is a new one for me, but then I have only built one tesla
> coil, so the whole hobby is new...
>
> Anyway, I was tearing down my tesla coil, as I had designed it so
> that I could take it apart to easily transport it if needed.  I was
> carrying the 4.5" diameter secondary with top load attached across
> the room when I noticed it had a charge on it.. The charge was
> minimal at first, like if you are building up a static electric
> charge on something, and then when I was half way into the room it
> crossed into a "hey.. Ow.. Let's put this coil down on this bench
> here" level of painful zap..
>
> My best guess is that I was picking up on the magnetic fields that
> were being put off by all the florescent lighting in the room. Either
> that or my movement some how built up a static charge.. But has
> anyone heard of/experienced something like this before.
>
> perl -e 's==UBER?=+y[:-o]}(;->\n{q-yp-y+k}?print:??;-p#)'
> _______________________________________________ Tesla mailing list
> Tesla@xxxxxxxxxx http://www.pupman.com/mailman/listinfo/tesla
>



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