Complex Imaginary Test 2 Problem 24

[Wildsoldier PE]

This problem is very similar to the NCEES problem 129. The errata for this problem clarify something that I think still is wrong because they forgot to multiply by square root of 3. I provide 2 methods to solve this problem. One is the Complex imaginary method the way i think it is supposed to be done and the other is using the NEC correction factor.

[SIZE=14pt]Method 1:[/SIZE]

[SIZE=14pt]Method 2:[/SIZE]

Let me know what do you all think.

 

[DK PE]

The method you have identified #2 is used as a good approximation in IEEE-141 voltage drop calculation and is generally speaking, quite accurate. I didn't plow through your original solution but it seems like that is the exact answer. There is an error term if you look in the IEEE standard which I think will bridge from your first solution to second. I am just guessing but I would think that applying the approximation on the test would give you a solution close enough to get you to the correct answer. If you look at the diagram in IEEE-141, you can see where the error comes from.

I assume you realize that the difference of 200mV in your two solutions is probably smaller than the tolerance in the provided conductor parameters?

 

[xd-data-ii]

Their latest errata clarifies asking for phase voltage in the question so their solution is correct.