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Re: buying a pole pig

Original poster: Don Murray <don@xxxxxxxxxxxxxxx>

Aaron,
It doesn't matter if that transformer is in the wild, up a pole or in your garage, that nameplate means that if you are going to attach that transformer to a 7200 phase to phase volt system you are going to connect it delta, and if you are going to connect it to 12470 phase to phase volt system, you're going to connect it Y. That is the only thing it can mean and because of that you know it's going to be a 2 bushing transformer. If it was a 1 bushing transformer it would only have one voltage.
As far as overvolting it, I don't doubt that you can get away with 2 times or even 3 times for a short amount of time. You just might not be so lucky on your second try. 

Don

Tesla list wrote:


Original poster: "J. Aaron Holmes" <jaholmes@xxxxxxxxxxxxxxxxxx>
In the wild, 7200/12470Y does *not* imply that a 7200V
delta connection is ok.  You also need the pig to have
two HV bushings.  If it has only one, then a delta
supply would imply that the can is "hot", which is no
good.
Regarding overvolting, I seem to recall the Aron and
Justin of www.hvguy.com not only overvolted a 5kVA
7200V unit to 14400V, but also pushed it up to 25kVA
for a Jacob's ladder.  It survived.  May have been
tempting fate, though.  I know the BIL rating of pigs
is for very short-duration spikes, but it's often for
10x (or more) the rated HV of the pig.  It seems hard
to believe, then, that running at only 2x (albiet
continuously) would compromise the insulation, but
obviously anything that risks causing your pig to
explode is BAD!!! :-)  Maybe if your pig has a
removable inspection plate in the lid (one of mind
does) then you should remove that before overvolting
:-))
Regards,
Aaron, N7OE
--- Tesla list <tesla@xxxxxxxxxx> wrote:
 > Original poster: "Gerry  Reynolds"
 > <gerryreynolds@xxxxxxxxxxxxx>
 >
 > Thankyou Don,
 >
 > This has been very informative.  I will read the HV
 > 7200/12470Y spec
 > to mean that you can connect the transformer across
 > any two phases
 > for a 7200 delta system or connect from any one
 > phase to ground for a
 > 12470Y system.
 >
 > Gerry R.
 >
 >
 > >Original poster: Don Murray <don@xxxxxxxxxxxxxxx>
 > >
 > >Hi Gerry R.
 > >   The bottom line is that that transformer can
 > only take 7200
 > > volts. Over volting it can cause arcing in the can
 > and that can
 > > cause acetyline gas to form in the can, very bad,
 > tends to blow the
 > > lid off next time there is an arc in the can.
 >
 >
 >
 >
 >