Re: Terry, Re: Protecting NST's

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

Original poster: "Terry Fritz" <twftesla-at-uswest-dot-net>

Hi Johathan,

At 01:57 PM 4/22/2001 -0700, you wrote:
>Terry,
>
>
>>The super killer of NSTs is using a resonant size primary cap and not have
>>the safety gap set right or not using a safety gap at all.  If the main gap
>>does not fire for any reason, the voltage will skyrocket to maybe 80kV!!
>>That will easily blow the NST as has been demonstrated 1000 of times...
>
>Thanks for the advice. I have to admit that I don't know exactly what a
>"resonant size primary cap" is. 

This is a "magic" value that will resonate with the NST's output.  The
voltage and current will resonate much like a TC and the power level can
get super high.  This is nice because it delivers a lot of power
throughput.  However, if something goes wrong and the gap does not fire,
the voltage and current will rise until something blows up.  There is
another ""Res. caps" post today.  Watch the answers on that.

snip...
>>3.  Put a fast blow fuse on the NST input.  When really large LTR cap
>>values are used, there is a very odd condition where the NST looses it's
>>ability to limit current.  This is believed to be due to the shunts in the
>>NST saturating and no longer being able to control current.  The output
>>current and voltage suddenly go to very high levels and the NST hums like
>>mad.  A fuse on the input will remove power if the NST starts to draw too
>>much current and stop this dangerous condition.  My small coil is very
>>close to this point.  I have tried to use this effect to get super powers
>>out of an NST "SLTR operation" but it just gets to scarry ;-))
>>
>
>What value should I use on the fuse?

Good question :-))  Probably 1.5 to 2X the NSTs input current rating.  That
depends on a bunch of stuff.  I would try lower values and go up, but 1.5X
should be close.  When the NST goes nuclear we are talking like 5X...  For
your 15/60 that should be around 10 to 15 amps.  You may have to test a few
in that range.  Too many variable to figure it out exactly easily...  Don't
be afraid to go to higher values since we are protecting against a really
huge dramatic current surge...

Cheers,

	Terry