[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

RE: buying a pole pig, wye and delta



Original poster: "Jim Mora" <jmora@xxxxxxxxxxx>

Hi Gerry,

Please explain what you mean by balancing being made up by the ground path
in a wye configuration. Since wye can be connected two BTW 2 phases rather
than to ground or for that matter a large load to any one ground. How does
this "balance things out load wise?

As you may know I'm build a three phase generator 20KVA delta 480v. This
will feed a delta to wye 208/120v transformer. My understanding that this
arrangement cleans up harmonics and make a closer to clean sine wave output.

This in turn can be used for emergency power or what I'm building it for is
a wye input configured 3 phase HV transformer.

I fail to see how load balancing is accomplished however.

Thanks for your input,
Jim Mora

-----Original Message-----
From: Tesla list [mailto:tesla@xxxxxxxxxx]
Sent: Tuesday, June 06, 2006 11:10 PM
To: tesla@xxxxxxxxxx
Subject: 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
>
>