Re: Ballasting a Pole Pig (Revisited)

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "J. Aaron Holmes" <jaholmes@xxxxxxxxxxxxxxxxxx>

Sounds ok to me.  My 25kVA unit has LV about .06 ohms
on each 120V winding, and 26.5 ohms across the HV
winding.

Still, this doesn't rule out internal arcing.  If the
pig with ballast in series always seems to draw the
maximum amount of current permitted by the ballast
(even with nothing across the HV), the pig is probably
a goner.  Again, if you haven't already, I'd pop the
lid off and take a look inside.  If something's arcing
internally, chances are good that the oil will appear
murky, perhaps with ribbons of carbon or other debris
suspended in it.  Otherwise, you should be able to see
all the way to the bottom of the can, no problem.

Here's a picture looking inside the can of a 25kVA
unit similar to my own which belongs to another local
coiler here in Seattle:

http://silicon-arcana.com/inside_rte.jpg

Oil is yellow in color, but very clear; you can see
all the way to the bottom of the can.

Hope it ends up working!!
aaron


--- Tesla list <tesla@xxxxxxxxxx> wrote:

> Original poster: Yurtle Turtle <yurtle_t@xxxxxxxxx>
>
> FWIW,
>
> I got 42.4 ohms on the HV side and .1 ohms on the LV
> side. Mine's a 240/14.4 kV 25 kVA pig with aluminum
> windings.
>
> Adam
>
> --- Tesla list <tesla@xxxxxxxxxx> wrote:
>
>  > Original poster: "J. Aaron Holmes"
>  > <jaholmes@xxxxxxxxxxxxxxxxxx>
>  >
>  > If you haven't already done so, you might try
> simply
>  > measuring the resistance of the pig windings,
> both
>  > the
>  > HV and LV.  Off hand, I can't think of what
>  > resistances would be "normal" for a pig the size
> of
>  > yours, and it probably varies quite a bit, even
> for
>  > pigs of the same rating.  Still, you should
>  > definitely
>  > *not* see a dead short or and open circuit on the
> HV
>  > side.  LV side may appear very close to a dead
>  > short,
>  > even if it is fine, however if you have a very
>  > accurate DMM then you may be able to measure the
> two
>  > 120V windings in turn (they should be the same)
> and
>  > then observe that the 240V lugs present double
> the
>  > resistance of the 120V lugs.
>  >
>  > Have you popped the lid on the pig to see if
> there
>  > are
>  > any signs of internal arcing?  Murky oil would
>  > definitely be a bad sign.  If, with the HV side
>  > unconnected, you cannot supply power to the LV
> side
>  > without tripping a breaker (even with no ballast)
>  > then
>  > something is definitely wrong.
>  >
>  > Another thing to be mindful of with pigs is that
>  > sometimes one of the LV lugs is not connected to
>  > anything inside the can.  This would be the case
> if
>  > the pig was used as part of a three-pack of
>  > transformers used to supply 208V three-phase
> power.
>  > In such an application, the two 120V windings are
>  > configured in parallel rather than series.  A
> look
>  > inside the can should make it obvious if this is
> the
>  > case.  If it is, then you may inadvertently be
>  > putting
>  > 240V into what should be a 120V winding, or you
> may
>  > effectively have one lead connected to nothing
>  > (though
>  > the latter would certainly not explain the
> breaker
>  > blowing!).
>  >
>  > aaron
>  >
>  > --- Tesla list <tesla@xxxxxxxxxx> wrote:
>  >
>  >  > Original poster: "C. Sibley"
> <a37chevy@xxxxxxxxx>
>  >  >
>  >  > I am unable to get any arc from the pig, at
> any
>  >  > power
>  >  > setting...
>  >  >
>  >  >
>  >  > --- Tesla list <tesla@xxxxxxxxxx> wrote:
>  >  >
>  >  >  > Original poster: "Gerry  Reynolds"
>  >  >  > <gerryreynolds@xxxxxxxxxxxxx>
>  >  >  >
>  >  >  > Hi Curt,
>  >  >  >
>  >  >  > Is the low voltage at t
msnip...