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Re: Toploads that bite
Tesla List wrote:
>
> Original Poster: Ross Ogden <rossoggy-at-yahoo-dot-com>
>
> I was unfortuanate to get a static electricity shock
> form the topload of my coil yesterday which felt like
> the time when i discharded a crt to my hand. I got it
> when i was removing it after a short run with the
> mains off. Ive heard this happens to other people too.
> It seems strange that about 15 Kv could build up on a
> topload which has a electrical resistance of 32 ohms
> to ground mesured(which proves there is no gap between
> secondy terminal and topload).
>
> Could my shock of been because the charge built up on
> me insted of the coil load. I was wearing rubber soled
> shoes.
>
> Any thoughts ?
>
> Ross Ogden
> Scotland
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Ross,
Let me guess... you picked up or touched the top portion of your
secondary, and then accidently touched the topload?? During operation,
the outermost coating of the secondary often acquires a heavy
electrostatic charge (particularly if you've got a heavy top coat of
polyurethane or epoxy over the winding). Ths charge has nowhere to go,
and "bleeds" away only very slowly. You may also notice that the top
portion of your coil behaves sort of like a "dust magnet" because of
this stranded charge. The stranded charges can linger for days or even
weeks after a run.
If you now rub your hands over these charged areas, your whole body
picks up the charge. If you are well insulated by your rubber-soled
shoes, you then get "zapped" as you discharge yourself to the grounded
topload. I've seen a spark about 1/4" long jump from my arm to the
topload after "repositioning" my 10" secondary - makes for quite a
surprise! Congratulations! You have now been initiated into the world of
coiling! :^)
-- Bert --