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Re: Grounding Question.

Original poster: Vardan <vardan01@xxxxxxxxxxxxxxxxxxxxxxx>


You can ground one side of the NST output to the frame and then ground that frame to the AC line ground. There is no problem with that.



At 06:25 PM 7/17/2006, you wrote:
I do have another question regarding grounding. I've attached two more pages from the apparently ancient TC design. The pictures illistrate the HV side of the NST's grounding to the same ground plate as the Secondary and Mains. We've already covered the secondary ground is a bad idea but what about the NST HV using mains ground?



On 7/17/06, Tesla list <<mailto:tesla@xxxxxxxxxx>tesla@xxxxxxxxxx> wrote:
Original poster: "Gerry Reynolds" <<mailto:gerryreynolds@xxxxxxxxxxxxx>gerryreynolds@xxxxxxxxxxxxx>

Hi Glen,

Just to summarize what others have said and add third comment:

1. Secondary base, center terminal of safety gap, and strike rail (if
used) need to be grounded to a separate RF ground (not connected to
mains ground). I like to also ground the NST (if located under or
very near the TC) to RF ground.  Any control panel/variac/sheet_metal
that you may come in contact with during operation needs to be
grounded to mains ground.

2. Chokes in series with the NST HV bushings is NOT recommended.  Use
the Terry filter (RC low pass filter to keep RF off the NST - see archieves)

3. The schematic shows C1 and C2 from line (and neutral) to mains
ground. This is suggestive of a line filter that I do
recommend.  However there is a limit on the size of C1 and C2 because
there is a limit on how much current can be in safety ground for
safety reasons in case safety ground opens up. Line filters usually
use a common mode choke to turn any common mode stuff on hot and
neutral into a differenctial mode signal that can easily be filtered
with a cap between HOT and NEUTRAL (no limit on size).

Gerry R.

>Original poster: "Glen McGowan" <<mailto:glen.mcgowan@xxxxxxxxx>glen.mcgowan@xxxxxxxxx>
>I'm building a TC from the attached schematic. From the looks of the
>drawing I'm double grounded. The secondary is grounded to the mains
>and earth. The NST's are all grounded via a shared grounding plate
>which is mains grounded.
> http://hot-streamer.com/temp/480W.jpg
>C1 and C2 are there to limit noise fed back into the house wiring
>(some of it at least). I understand that grounding the secondary to
>the grounding plate can produce lethal currents but is there any
>advantage to doing this?  This may be a rhetorical question. I
>assume the secondary would "choose" the earth ground before it
>reached the mains ground because earth would be the shortest
>distance. But according to the drawing the NST's HV and LV's are
>both using the mains ground as is the secondary (has a "choice" of
>using mains or earth).
>I apologize if the post was hard to follow. I've scratched the same
>spot on my head for the past hour. It's starting to bleed.