# NCEES #524



## robertplant22 (Feb 11, 2012)

Why are the copper losses multiplied by 4 and not by 2 in the solution to this problem? The question is as follows:

A power transformer has the following test data at rated voltage:

% of Nameplate kVA Total Losses (W)

 0 460

 50 2,370

The total transformer loses (W) at 100% of nameplate kVA are most nearly?

In this question I understand that the Core losses are Pcore= 460W. I also understand that to find the Copper losses, Pcu,50% at 50% loading you need to subtract the Core losses (Pcore= 460W) from the Total losses (PT,50% = 2,370W); therefore:

Pcu,50%= PT,50% - Pcore= 2,370W - 460W = 1,910W

Here is the part I dont understand:

Pcu,100%= (4)(Pcu,50%) + Pcore = (4)(1,910W) + 460W = 8,100W


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## robertplant22 (Feb 11, 2012)

It seems as though the formatting got change from when I typed the message; the table read

At 0% kVA rating, Total losses are 460W

At 50% kVA ratin, Total losses are 2,370W


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## Power12 (Feb 11, 2012)

Look at this thread

524


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## robertplant22 (Feb 11, 2012)

Thanks. The thread clarifies this. How did you find the thread; I tried doing the search for "NCEES #524" and the serach returns nothing!

Thanks again.


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## knight1fox3 (Feb 14, 2012)

robertplant22 said:


> Thanks. The thread clarifies this. How did you find the thread; I tried doing the search for "NCEES #524" and the serach returns nothing!
> 
> Thanks again.


When I was studying, if EB.com didn't find anything I searched for, I tried Google where I would search for "NCEES 5## engineerboards.com" or a variation there of. And if something existed, it would usually come up there.


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## robertplant22 (Feb 14, 2012)

knight1fox3, thank you for the tip. It works like a charm!


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## kris7o2 (May 24, 2021)

The thread above no longer works. Does anyone have the new link?


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## akyip (May 24, 2021)

Use this link:









NCEES Power PE exam # 64


Can anyone explain this to me? No sure what's going on.




engineerboards.com





I posted my explanation of the solution to this problem on this link.


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