# New NCEES (Power) #125



## ndekens (Feb 3, 2009)

Ok so I have no notes or study material nor can I find any on the inner-net that explains the what how and whys of this problem. Can anyone on hear do this??? How are you suppose to know that the transformers will load in inverse proportion to there impedances?? .......Im lost. Thanks!


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## Flyer_PE (Feb 3, 2009)

The equivalent circuit is just like two resistors in parallel. Current will take the path of least resistance. One important detail is that you have to get all of the pu impedance values on a common base.


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## Flyer_PE (Feb 3, 2009)

This problem was #525 in the old book. There is some discussion of it here.


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## cabby (Feb 4, 2009)

I stumbled across this on the web. It is another way of working the problem.

http://ecatalog.squared.com/pubs/Electrica.../7400DB0701.pdf

cabby


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## visu212 (Apr 21, 2009)

Flyer_PE said:


> The equivalent circuit is just like two resistors in parallel. Current will take the path of least resistance. One important detail is that you have to get all of the pu impedance values on a common base.


Flyer PE, Please find the attached solution converting to both bases.....please let me know what mistake I am doing here.


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## Flyer_PE (Apr 21, 2009)

Take a look at the attached file and see if it helps. Sorry for my lousy handwriting.

Problem125.pdf


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## dianevp (Mar 24, 2011)

cabby said:


> I stumbled across this on the web. It is another way of working the problem.
> http://ecatalog.squared.com/pubs/Electrica.../7400DB0701.pdf
> 
> cabby


Here's the new link: http://static.schneider-electric.us/docs/E.../7400DB0701.pdf


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## Dolphin P.E. (Mar 24, 2011)

Flyer_PE said:


> Take a look at the attached file and see if it helps. Sorry for my lousy handwriting.
> Problem125.pdf


Flyer_PE, I am not sure about the statement in attachment which says " Due to its higher impedance, the 1 MVA transformer will reach full load first" . I think it should say: '' Due to its *lower* percentage impedance (impedance based on the transformer base values), it will reach full load first.


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