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Re: buying a pole pig

Original poster: "Gerry  Reynolds" <gerryreynolds@xxxxxxxxxxxxx>

Hi David,
If the delta system was 12470 across two of the three phases, this would be identical to a Y system that had 7200V in each leg (referenced to ground) in that the voltage across two of its three phases would also be 12470V. Sounds like if the pig were hooked to 7200V across its 2 HV bushings and delivered 120Vac on the parallel LV configuration, then it would deliver 208 Vac in the same LV configuration when hooked across 12470V on the HV side. If one were to drive the LV with 240V in the parallel LV configuration, the output would be 14400V. If the core can safety take the 12470/208 without saturating then maybe there's hope for the 14400/240 operation.
In terms of the sematics of the meaning of 12470Y, one could connect the pig across two phases of a Y system just as easily as a delta system so maybe this nomenclature is just fine. BTW, what is common in the USA, Y or delta or both?? With delta, the loads across each pair of phases needs to be balanced else the currents on one of the phases could be excessive. In a Y system, any unbalanced currents are made up for by the ground path. 

Gerry R.





Original poster: DRIEBEN@xxxxxxxxxxxxxxx
Gerry,

I am no EE or a specialist in electrical
power distribution but it is my understanding that
the "Y" rating is only for a 3-phase delta hookup
where the input HV bushings are just crossed between
two of three phases. I agree with what Mike Marcum
also stated in that the "Y" rating is actually the
"delta" voltage rating and it seems that pigs "Y"
rating should actually be the lower of the voltages
(12470/7200Y as opposed to 12470Y/7200) since the
12470 volts would only be seen in a delta cross
phase hookup.

David Rieben

----- Original Message -----
From: Tesla list <tesla@xxxxxxxxxx>
Date: Tuesday, June 6, 2006 1:55 pm
Subject: Re: buying a pole pig
To: tesla@xxxxxxxxxx

> Original poster: "Gerry  Reynolds" <gerryreynolds@xxxxxxxxxxxxx>
>
> Hi David,
>
> Seems like he could drive it with 240 and get the 12470 rating.
Yes??
>
> Gerry R
>
>
> >Original poster: "David Rieben" <drieben@xxxxxxxxxxxxxxx>
> >
> >Justin,
> >
> >The "Y" refers to a wyed cross phase hookup in a
> >three phase configuration. 12,470 is the sq. rt. of 3
> >x 7200 volts. In single phase configuration, the 7200
> >volt rating is all that you will be getting and 7200 is
> >a little on the low side for a 15 kVA SG driven Tes-
> >la system, but hey, if it's free, then go for it.
> >
> >David Rieben
> >
> >
> >----- Original Message ----- From: "Tesla list" <tesla@xxxxxxxxxx>
> >To: <tesla@xxxxxxxxxx>
> >Sent: Monday, June 05, 2006 10:15 AM
> >Subject: Re: buying a pole pig
> >
> >
> >>Original poster: Justin <rocketfuel@xxxxxxxxxxxxx>
> >>
> >>
> >>Hi All,
> >>
> >>Just an update, here are the specs on the pig:
> >>
> >>15KVA
> >>Rated Volts: 7200/12470Y        120/240
> >>2.2% impedence
> >>Orto Filled
> >>
> >>http://jay.g-cipher.net/pig2.jpg
> >>http://jay.g-cipher.net/pig1.jpg
> >>
> >>
> >>I'm curious what the Y means in the "12470Y"...any ideas?
> >>
> >>
> >>
> >>Thanks as always!
> >>
> >>Justin