Re: Counterpoise and MMC demise

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

Original poster: "Barton B. Anderson by way of Terry Fritz <teslalist-at-qwest-dot-net>" <classictesla-at-netzero-dot-com>

I know I'm not the only one who has needed to clean the gap once or twice. 
Should a missed firing occur for "whatever reason", and the transformer has 
the oomph, it will continue to charge the cap on the next 1/2 cycle up 
until conduction occurs (or a failure at the cap or NST). But, static gaps 
are highly unlikely to break mechanically. Material transfer such as we see 
in relays would also occur in static gap electrodes and should cause a 
point charge and lower breakdown. But, there are many possibilities 
(humidity, pressure, burning material, soot, erosion, and probably many 
other things not listed which could cause higher or lower breakdown.

The bottom line is to avoid the temptation of opening the gaps too wide 
(test the breakdown voltage when setting up the gap width), ensure the gap 
is mechanically sound, and periodically inspect, clean, and keep a smooth 
conduction surface. Make that routing, and the likelihood of NST or cap 
failures due to overvolting is greatly reduced.

Bart

Tesla list wrote:

>Original poster: "Finn Hammer by way of Terry Fritz <teslalist-at-qwest-dot-net>" 
><f-h-at-c.dk>
>
>Stephen.
>
>I am sorry to hear of your loss, but there is no reason to add to the
>myths, such as that the breakdown voltage of a static gap suddenly
>increases. It doesn`t.
>Cosmic rays (  :-)  ), uv photons, heat, all make the gap fire at a
>lower voltage than that of the stone cold one. The litle droplets of
>molten copper that form on the copper pipe gaps when they get really hot
>also makes the gap fire at lower voltages, often so low that the
>breakrate rises to a fizzing high .
>I would think that dv/dt looks like an almost standstill from the gap
>point of view, nomatter what breakrate, but I am not sure.
>
>What breaks caps and transformers is the lust for longer streamers,
>which makes the coiler increase the spacing of the gap, and thus the
>breakdown voltage of it,  beyond the limits of the cap and transformers
>ratings.
>
>It is a problem of inadequate measuring equipment, rather than one of
>gap unreliability.
>
>Cheers, Finn Hammer
>
>Tesla list skriver:
> >
> > Original poster: "Stephen Conner by way of Terry Fritz 
> <teslalist-at-qwest-dot-net>" <steve-at-scopeboy-dot-com>
> >
> > At 18:37 19/06/03 -0600, you wrote:
> >
> > >??  If the gap is set to fire at some voltage it will fire at that
> > >voltage. The cap can't ring up beyond that voltage.
> >
> > That ain't so... There is a lot of uncertainty in the firing voltage of
> > static gaps, it varies depending on dv/dt, electrode temperature, and
> > whether a cosmic ray or U.V. photon happened to hit the electrodes as the
> > voltage was at its peak. The uncertainty is easily enough to let the cap
> > ring up to voltages that will kill your NST power supply, as several people
> > myself included have found out the hard way :(
> >
> > Steve C.
>
>
>
>