Somebody please help me understand NCEES 522

[danderson]

I am absolutely dying on this one.

Why is the phasor V = (jXs)(Is) + Ei and not V = Ei - (jXs)(Is)?

I flat can't figure this one out.

BTW, if anyone wants to make some money, you should sell a book with solutions to the NCEES practice exam that you can actually understand.

 

[katag]

The phasor is V=(jXs)(Is) + Ei because it states that it is acting as a motor. If it were acting as a generator it would be V=Ei-(jXs)(Is). If you can find a picture of the equivalent circuit for a synchronous generator and motor then I think it will be more clear as it is just using Kirchkoff around the loop. I don't know which books you have for resources but the Wildi book and the Chelapati book both have diagrams that show the circuit. I hope this helps!

 

[danderson]

I have Camara and neither of the ones you mentioned. If I have to retake the exam, I will be getting at least one of the two you mentioned. I have very little good to say about the PRM. I've gotten better stuff out of my college electro-mechanical textbook.

Thanks for your help.

 

[danderson]

The PRM has what you need, there is just so much blathering about things that do not matter to the PE in the book it makes the important stuff easy to overlook.

 

[Peele1]

I kinda like the EERM/PRM from Camera... Not perfect, but a good reference manual. With it, I only had a stack 14" tall of books, as opposed to some people with 2-3 feet of books at the PE exam. Part of it has to do with your familiarity with the resource. If you like your college texts, and know where things are, good. If you are like me, and have none of my college books, the EERM was awesome.

 

[thammond]

In the NCEES solution it state the following: Ei=1-.9x1.05 at an angle of (90-18.19)

My question is where did the 90 degrees come from?

Thanks for the help

 

[thammond]

I got it, from changing j.9 to polar,

Sorry need to slow down and think

Best of luck to all

 

[ruffryder]

I got it, from changing j.9 to polar,

Sorry need to slow down and think

Best of luck to all

No doubt going too fast can cost you a lot on questions. I answered some questions with total 3 -phase power when single phase power was asked. Got to make sure I answer the problems I know how to do correctly, correclty.