Re: record sparks then nothing

Hi Bob,

	Very sorry to hear of your damaged transformer.  Resin filled neons or
pretty rare so you should be able to get the tar out and fix it with luck.

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.

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 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.



At 10:53 PM 10/24/1999 +0100, you wrote:
>Hi All,
>	Tried a bit of tuning on my coil today and got regular 36" sparks to a
>grounded rod. Great I thought then I decided to move the coil slightly as I
>was getting too close to the wall. Wound up the variac again and it ran for
>a few seconds then tripped the mains. Darn I thought. When I looked at the
>coil I noticed that the ground lead had become disconnected,so i had been
>running without a ground for a few seconds at least. I dismantled the
>system and got the megger out. It seems that I have got an ground fault on
>one of the primarys of one of the trannys They are GE 10 kV 50mA they look
>quite old but hopefully they are tar filled rather than resin filled.
>anybody ever dismantled one of these? Oh well looks like it is back to the
>9 Kv 50 f.a.r.t. again for the teslathon unless I get time to sort out my
>radar transformer. That will teach me to be to be too keen to squeeze the
>last bit of spark out!!
>bob golding