PPI Exam 1 question 38 - is the given solution correct?

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akyip

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Hey guys,

Can you please take a look at PPI exam 1 question 38 and its solution, and see if you agree with the solution?

My initial attempt was that since the load power factor = 0.8 lagging given, the load angle theta = theta voltage - theta current = 36.87 degrees.
Then on the transmission line side, which is the transformer T2 high-voltage primary side, since the standard is that the HV side leads the LV side by 30 degrees, theta line = 36.87 + 30 = 66.87 degrees.

But this is incorrect according to the solution.

According to the solution, the load angle theta = -37 degrees, and the angle between voltage and current on the transmission line is actually -7 degrees. I can't say I really agree with this solution since the -37 degrees is actually the current angle, and the +30 degrees refers to the overall phase angle between voltage and current, not the current angle...

What do you guys think of the solution to this problem? Is there something I'm missing here?

PPI Exam 1 Q 38.jpg

PPI Exam 1 S 38.jpg

 
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