Re: Safety Gap Question

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

Original poster: "Jason by way of Terry Fritz <twftesla-at-qwest-dot-net>" <jasonp-at-btinternet-dot-com>

Malcom,

> If the safety gap is placed directly across the main gap, why is it
> needed at all (think about it)?

I have thought about it... I think what you are referring to is a
non-grounded gap, i.e. just an alternative route for the cap to discharge if
the RSG stops functioning for any reason. I am talking about a three horned
gap with the centre point grounded to RF ground so that the current will go
to ground rather than through the primary.

> The real problem occurs when the
> transformer is positioned some distance away from the main gap. The
> long leads running between the gap and transformer form a
> transmission line which is quite capable of generating high voltages
> with very little energy given the high shunt impedance of the
> transformer terminating it at the far end. Ergo, the safety gap
> should be placed directly across the transformer secondary terminals
> and secondary ground if the secondary is grounded.

Point taken - I use an RSG with a neon, and i know how important it is to
have an SSG :) I use a Terry style protection filter that incorporates large
resistors. If I put the SSG across the transformer then I would run the risk
of damaging the resistors as well as overcharging the caps. My cap bank is
also practically resonant (10/140 35nF) so I always put the SG across the
past of least resistance and inductance. The high impedance of the neon plus
the impedance (and inductance) of the resistors actually makes the SSG more
effective when it is across the gap as less gets back to the neon. I am also
not sure what you mean by the transmission line 'generating high voltages'
though... as far as I am concerned it's just a conductor.

Regards,
Jason