Re: Weird coil behavior

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Steven Ward by way of Terry Fritz <twftesla-at-qwest-dot-net>" <srward16-at-hotmail-dot-com>




>From: "Tesla list" <tesla-at-pupman-dot-com>
>To: tesla-at-pupman-dot-com
>Subject: Weird coil behavior
>Date: Wed, 12 Jun 2002 21:34:06 -0600
>
>Original poster: "Sean Taylor by way of Terry Fritz <twftesla-at-qwest-dot-net>" 
><taylorss-at-rose-hulman.edu>
>
>Hi all -
>I was running my coil last night, and decided I wanted a little longer
>sparks and pushed it to the limits, so I added one more gap to my RQ type
>gap.  Took a little more on the variac to get it to fire, as expected, but
>when it did fire, It seemed like I got arcs through the _inside_ of my 
>coil,
>and from the secondary to the primary.  But these weren't like normal arcs
>from a coil, they fired like a HUGE discharge of energy, making an
>incredibly loud noise when the did occur.  After seeing all of these things
>happening, I shut it off, and lowered the # of gaps back to normal.  
>Brought
>the variac up again and . . . nothing.  just transformer humming, a little
>crackle noise from the gap like corona.  I kept reducing the gap size until
>I was at one gap (about 0.030") and then it would fire with a high setting
>on the variac, but no output from the TC.  I disconnected everything, and
>checked each component (transformers, cap, primary connections, etc) and
>everything was fine.  There were no carbon traces through the PVC 
>secondary,
>but there was a burn through one turn of the secondary, basically acting as
>a shorter turn.  Shouldn't the gap still fire?  Anyway, here are the specs
>of my coil . . .
>
>4 x 15 kv, 30 mA NSTs
>Rolled PE cap, ~0.02 uF (I know its small, I'm getting a new cap soon)
>RQ style gap, ~0.03" per gap, 5 gaps when problem occurred
>inverse conical primary (~20 degrees), 1/4" copper tubing, 1/2" CTC spacing
>6" PVC secondary, 22 Ga. wire wound on about 28"
>
>Thanks in advance for any help!
>Sean Taylor


Maybe you blew the cap, but since the poly is so thick, the higher gap 
settings cause it to arc internally, while a small gap setting will break 
down rather than inside the cap.  Transformers are easy enough to check, and 
the other components are simple enough to inspect. I would think that a 
punchthrough, wouldnt be detectable with a meter.  I get all kinds of 
primary arcs, and some internal secondary arcing at times(needs insulation) 
but it has never caused any problems.  Thats the best answer i can think of.

Steve Ward.

_