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=?iso-8859-1?Q?Re:_Finally_got_around_to_sync=B4ing_my_async?= motor

At 05:32 PM 4/24/99 +0100, you wrote:
>SNIP
>
>Unfortunately I have just destroyed my NST using it :-(
>By the way my NST is Italian and potted.
>
>Regards
>
>Viv Watts UK
>

Since there is so much new interest in using rotary gaps with NST systems,
perhaps we should once again repeat the old warning about safety gaps.

Resonant charged NST systems will develop huge voltages across the primary
cap and transformer.  This super high voltage will easily destroy the cap
and/or transformer.  In a static gap system, the gap will ALWAYS fire and
save the day.  However, rotary gap systems can easily not fire in time to
prevent the voltage buildup and BANG!... there goes the transformer.

The solution is simple, just have a static safety gap across the
transformer or cap.  If the rotary decides not to fire, the safety gap will
step in and drain the voltage before it reaches destructive levels.

I ran a Microsim model of what would happen if I ran my 15kV 60mA neon at
120 volts input with only a 10nF cap across the output.  After 0.181
seconds the voltage peaked at 247kV and the output current peaked at 0.94
amp!!!  I can only assume that something (like core saturation) would limit
a real transformer before it got to this 200+ KVA output, so the model is
probably not real accurate at all.  However, the destructive effects of not
having a gap fire in such a system are obvious.  I don't think I'll check
this one in real life! :-))

Cheers,

	Terry