A complex load across 2 phases - PPI Exam 1 Question 8 and NCEES Exam Question 110

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akyip

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Hey guys,

I would like to get your input on whether Problem 8 from PPI Exam 1 is worded correctly compared to its solution.

PPI Exam 1 Problem 8 states: "A complex unbalanced load of 500 + j300 VA is connected across Phase A and Phase C." This question asks for the neutral current.

When I saw that statement, I was thinking only one complex load (S 1-ph) connected across Phases A and B, so its voltage should be line-to-line voltage V AC (or V CA).

But when I look at the solution for Problem 8, it has I N = I A + I C = (S A / V A) + (S C / V C). That means 2 loads, one connected between A and N, and one connected between C and N. To me, this differs from what is stated by the Problem 8 statement.

What do you think?

Also, the NCEES practice exam has a problem (NCEES question 110) with one complex load connected across 2 phases. It's why I thought of that when I first saw this PPI exam problem.

What are your thoughts?

PPI Exam 1 Q 8.jpg

PPI Exam 1 S 8 Part 1.jpg

PPI Exam 1 S 8 Part 2.jpg

 
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