Re: Pig setup help.

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

Original poster: Bart Anderson <classi6-at-classictesla-dot-com> 

Hi Gerry,

Tesla list wrote:

>Original poster: "Gerry Reynolds" <gerryreynolds-at-earthlink-dot-net>
>Hi Bart, John and others,
>
>This issue of whether to ground the transformer case (whether it be a pig or
>NST) to mains ground or dedicated RF ground seems to be a reoccuring
>question that I think has no right or wrong.  I know there are opinions on
>both sides and valid ones.  Each solution has its benefits and problems and
>how one treats this issue depends on how they define their system.  The
>following are the benefits and problems as I see them:
>
>Transformer grounded to mains ground (green wire):
>
>Benefit:  transformer fault (like primary to case short or secondary to case
>short) may draw excessive current and blow breaker (note that the balast for
>a PIG or PT may not allow this to happen unless ground fault protection is
>used).  Case is safer, however one still has the bushings that can kill.
>
>Disadvantage:  A strike to the TC primary (transformer secondary) could
>flashover to the case and thus the mains ground and kill sensitive
>components (TV, stereo, etc) also plugged into the mains.

It is possible, but this is true with both configurations, including 
floating configurations. The lowest impedance will feel the brunt of the 
hit. Also, consider strike rings tied to rf ground (for all those folks who 
use them).  A probability factor comes into play by an increase frequency 
of hits (and you will get an increase in primary directed hits if a strike 
ring is used, and at times, the primary will get hit as well (especially 
for coils with poor field control). I just prefer to minimize the 
possibility's.
Take care,
Bart

>Transformer grounded to dedicated earth ground (aka RF ground):
>
>Benefit: a strike to TC primary that results in flashover to transformer
>case will directly return to the secondary ground and not contaminate mains
>power.
>
>Disadvantage:  transformer fault could result in a HOT case and no blowing
>of the breakers if the dedicated earth ground is not adequate.  If adequate,
>the protection should be just a good as mains ground, but still no
>guarantees for the balasted pig or PT unless ground fault protection is
>used.
>
>I think one should define danger zones in their system design.  If the
>transformer is within the danger zone,  grounding to the dedicated earth
>ground is OK.  If outside the danger zone, the transformer should be
>grounded to mains ground and the bushings protected from accidental contact.
>
>One persons opinion,
>Gerry R




> > Original poster: Bart Anderson <classi6-at-classictesla-dot-com>
> >
> > Hi Randy,
> >
> > Grounding the case to mains ground is for safety. All equipment with
>direct
> > feeds should have their case connected to mains ground (this includes the
> > transformer). In the event of a fault, we don't want the case at a
> > potential that could be lethal. Should there be a fault, the mains breaker
> > will trip and remove all power.
> >
> > Take care,
> > Bart
> >
> > Tesla list wrote:
> >
> > >Original poster: "Randy & Lori" <rburney6-at-comcast-dot-net>
> > >Bart,
> > >
> > >Why the "mains" ground? I have read:
> > >2 or 3 RF Grounds
> > >1 Mains Ground
> > >1 Mains OK if filter is used
> > >
> > >Randy
> > >
> > >-----Original Message-----
> > >From: Tesla list [mailto:tesla-at-pupman-dot-com]
> > >Sent: Saturday, March 13, 2004 12:44 AM
> > >To: tesla-at-pupman-dot-com
> > >Subject: Re: Pig setup help.
> > >
> > >Original poster: Bart Anderson <classi6-at-classictesla-dot-com>
> > >
> > >Hi Steve,
> > >
> > >Tesla list wrote:
> > >
> > > >Original poster: "steve" <steve_vance-at-cablelynx-dot-com>
> > > >I have a question for the list. I have a 10 kva pig I'm running
> > > >at 5 kva to power my coil my 6.5 inch coil. I was reading the archives
> > > >and came across a post about running one of the hv bushings and
> > > >the can to earth ground. Can't find enough information to convince me
> > > >that I fully understand how to do this safely. Someone correct me if
> > >I'm wrong
> > > >on this.... I run one of the hv leads to the can, ground the can to
> > >earth, run
> > > >the other hv lead to one side of the tank circuit, and the other side
> > >of
> > > >the tank
> > > >goes to the rf ground? Or does it need it's own ground rod?
> > > >
> > > >Thanks for any help.
> > > >
> > > >Steve Vance
> > >
> > >You've got it right. The case should be tied to "mains" ground. Then,
> > >240
> > >to the 2 low voltage bushings.
> > >
> > >To bring the inner primary at the same potential (RF ground) as the
> > >bottom
> > >of the secondary, tie one side of the hv terminal to RF ground and the
> > >other end to the tank. The hv terminal to RF ground does not need it's
> > >own
> > >ground. RF ground is where the connection is.
> > >
> > >Take care,
> > >Bart
> > >
> > >
> > >
> > >
> >
> >
> >
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