Re: Pig setup help.

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

Original poster: Esondrmn-at-aol-dot-com 

In a message dated 3/14/04 8:47:54 PM Pacific Standard Time, 
tesla-at-pupman-dot-com writes:

Gerry,

I could not decide which way to go when I first set up my 5 kva 14.4 kv 
transformer.  I ended up using the mains ground only for the line 
filter.  The variac cases and the transformer case are tied together and 
connected to a separate ground rod system located close by.  The secondary 
coil base and primary strike rail are connected to their own independent 
ground rod system located close to where the coil is set up.

The weak link I suppose is to make sure the 60 hz ground always has good 
connections and wet soil for the ground rods.

Ed Sonderman

>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.
>
>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