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Re: [TCML] 1KVA Pole Pigs?



Hi Conor,

There are indeed small, oil-immersed, "pole pigs" that are rated for 0.5 - 3.5 kVA. These are called "Fixed-Load" or "Potential Equipment Transformers" (smaller, housebroken "PETs", as opposed to "pigs"?). They're typically used to provide smaller amounts of power for control circuitry or lower power lighting circuits, and they're output voltage is 120, 240, 240/120. Applications include utility circuit reclosers, switched PFC capacitor banks, remote traffic signals, remote (and small) sign lighting, etc.

These transformers are "mini-me" cousins of full-fledged power distribution transformers, but they may only weigh 75 - 150 pounds. They are less expensive, draw less magnetizing current, and are more closely suited to lower power loads, so they often provide a more cost-effective solution than a heavier 10 or 15 KVA distribution transformer and where the accuracy and cost of a true potential transformer would be overkill.

Some providers of these include:
http://midcentralelectric.com/main.html
http://www.langley-eng.co.uk/langley_products/Fixed_load_transformers.html
http://www.specialtytransformers.com/ST%20Acrobat/PET%20BROCHURE.pdf

Bert
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ConorPerry@xxxxxxxxxxx wrote:
I was looking at a large coil (24" secondary) tonight which uses two
7200 volt pole pigs in series.  The tags showed "1.0 KVA" and "1 KVA"
on the other at 7200.  One had a weight listed of 88 pounds.  I've
previously measured these transformers pulling 20amps each (120 each
feed from two legs and neutral of a 208 3-phase system).  Now running
them phase shifted doesn't seem like a good idea, but I have no
science to backup why I think so.

My question is, "1 KVA" really?  I didn't think they made pigs that
small.  How did they survive at all running nearly 2.5 times their
rating?  One is now dead with a shorted secondary. Looks like it will
be hard to find another to matchup this pair again.

One pig is labeled "Fixed Load Transformer", what does that mean?

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