RE: Why does running an NST on an async gap kill it?

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

Original poster: "Lau, Gary by way of Terry Fritz <teslalist-at-qwest-dot-net>" <gary.lau-at-hp-dot-com>

Safety gaps should be applied only in parallel with the main gap and/or NST 
secondary.  Prior to firing, the main gap sees exactly the same voltage as 
the cap does.  The capacitor does not ever see a voltage that exceeds what 
is across the main gap.  So a safety gap across either the cap or the gap 
will be equally effective at clamping an overvoltage condition.

But, the vital difference is that when the safety is across the gap, should 
it fire, the energy from the cap will be transferred to the primary and 
secondary circuits, just like a main gap discharge, which is just fine.  If 
the gap were across the capacitor, there is nothing to limit the discharge 
current except the very low impedance of the arc, and the cap will see VERY 
unhealthy discharge currents.

Gary Lau
MA, USA

  > Original poster: "Mudford, Chris by way of Terry Fritz
<teslalist-at-qwest-dot-net>" <chris.mudford-at-agresearch.co.nz>
  >
  > Hi Gerry
  >
  > In what configuration would one set a safety gap across an MMC
  > capacitor?
  >
  > Cheers, Chris (NZ)