Re: record sparks then nothing

To: tesla-at-pupman-dot-com
Subject: Re: record sparks then nothing
From: bob golding <yubba-at-clara-dot-net> (by way of Terry Fritz <twftesla-at-uswest-dot-net>)
Date: Tue, 26 Oct 1999 11:43:22 -0600
Approved: twftesla-at-uswest-dot-net
Delivered-To: fixup-tesla-at-pupman-dot-com-at-fixme

At 20:18 24/10/99 -0600, you wrote:
>
>I was curious about two things.  Did you have a safety gap across the neon
>between each high voltage terminal and ground?  I would think that would
>have saved it.

Hi Terry,
	thanks for the commiserations. I was using two 110 volt neons with their
primarys in series and their secondarys in parralel. I did have a safety
gap between each side of the paralleled outputs, but as non of it was
grounded the current from the bottom of the secondary (of the coil) didn't
have anywhere to go.

>Also, you say the "primary" of the neon is shorted to ground?  Usually, one
>of the high voltage "secondary" windings fails.  I just wanted to be sure I
>got it right.

I checked again with the megger and it seems that both the secondary and
the primary are reading  a direct short to earth. I don't know why this is
until I get the tar out. 

>I try and design systems to be pretty bullet proof so they can survive a
>number of imaginable mishaps, but I never considered this before.  I would
>like to study what happened to see if such things can be prevented.

Yes designing for all possible "incorrect user input" conditions is really
hard. Espesaley when the user is not paying attention. The last time this
happened I got a arc between the bottom of the seconary and the primary as
soon as I started to turn up the variac,but this time all seems fine until
the earth leakage trip dropped out.
I am now back up to 28" sparks with the remaining 10 kV 50mA transformer,I
am using 23 nF of mmc cap on it.so should be ok for the teslathon,as long
as I remember that it is 110 volt and not 240!! I might put a step down
transformer on it, or a bolt on the variac  to stop me winding it up  too
far. Don't want to kill the other transformer as well. I did try 2 of the
obits in parallel with 10 nF and got 12" sparks but I have the individual
strings of the cap too close together and  I am getting arcing between the
strings. This is not normally a problem as I have all five strings wired in
parallel. something to note when I make my next mmc. 

still having fun in Cambridge UK 
bob golding