Re: SAFETY GAP CONNECTIONS

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Barton B. Anderson" <bartb@xxxxxxxxxxxxxxxx>

Hi Ed, All,

A thought just ran through my brain pan as the Merlot passed by:

Not all NST's are capable of tying the hv terminal low (rf ground). 
If the secondary center tap is tied to the case, then you would only 
have 1/2 voltage from the NST (the rf ground side would be null and 
void). In those cases, a 3 terminal gap would be necessary. However, 
all potential and distribution transformers should be fine with the 
hv terminal tied to rf ground.

Just thought I should mention that since I referenced the method.

Take care,
Bart

Tesla list wrote:

> Original poster: "Barton B. Anderson" <bartb@xxxxxxxxxxxxxxxx>
>
> Hi Ed,
>
> I showed my preference hookup in the related post. I prefer a 2 
> terminal system to be at rf ground, one output tied to rf ground, 
> and the case of the transformer at rf ground as well. Same would go 
> with a 3 terminal safety gap system. The rf ground side is noisy and 
> I don't think anyone would argue against that, but the noise is not 
> reflected back on mains ground when mains ground ends at the control 
> power cabinet and rf ground is at the transformer case. I agree, the 
> case center tap and center terminal of the safety gap should "not" 
> be separated.
>
> However, I don't see a perfect system out there. There are reasons 
> on both sides of the old argument "where does mains ground end and 
> rf ground begin". For myself, I want them separated. So, I chose to 
> keep all hv situations on rf ground and the low voltage side at 
> mains ground. For this to occur, mains ground must end at the control panel.
>
> Take care,
> Bart
>
> Tesla list wrote:
>
> > Original poster: Ed Phillips <evp@xxxxxxxxxxx>
> >
> >    From some of these discussions I get the impression that there 
> > is a recommendation that with a "two-gap" system protecting an NST 
> > the center terminal of the gap should go to "an RF ground" 
> > SEPARATE from the center tap (usually case) of the NST.  That 
> > sounds wrong to me as I can't see how such a connection would 
> > necessarily protect the transformer from inadvertent over voltage 
> > conditions.  Connection to the center tap AND a good RF grounds 
> > makes more sense.
> >
> > Ed