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Re: buying a pole pig



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

Hi Don,

So what is the bottom line on a PIG with a HV spec of 7200/12470Y. With regard ONLY to what the PIG can take, can you put 12470 across the two HV bushings??? (no consideration to what kind of service you want only what the PIG can take).

Gerry R.


Original poster: Don Murray <don@xxxxxxxxxxxxxxx>

Justin,
   What the Y means is that if you are going to connect that
transformer to a 12470 volt system you must connect it Y. Each end of
that Y is one phase of a 12470 volt system and each leg of the Y
would be one 7200 volt coil. On a delta system each corner of the
triangle is one phase of a 7200 volt system and each side would be a
7200 volt coil. Draw it out and you will see. What determines if we Y
or delta the high side is coil rating and primary voltage, if they
are the same it will be delta, if primary is higher it will be Y or
star as they are the same. And what determines if you get a delta or
Y low side is the service voltage you want. If you want 120/240 it
will be delta, if you want 120/208 it will be Y.

On the high side of a Y connected bank of transformers you don't
always ground it. Some times you let it float. And you don't always
have to have 3 transformers, you can have open delta and open Y with
2 transformers.

I have some transformer connections on my web page that I put up for
a discussion on a usenet group, thought they might help some. The
Scott connection at the bottom of the page is for 3 phase to 2 phase.
They take special transformers and are pretty rare.

http://murrayranch.com/Electricity.htm

Don

Tesla list wrote:
>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
Snip>