NCEES# 509

[Mohammed Ahmed]

Hi Gents,
I tried to solve this question about two Wattmeter method, my answer to get W1 &W2 equations was in different from the answer given in the NCEES practice book,
I know the answer is the same for both equations if PF=1, but I want to get the right equation in case if the power factor is different..
Anyone can help if I did any mistake in my answer?

 

[LyceeFruit PE]

1. Not all of us are gents.
2. Per the search function, here's all of the other posts about this question: Search results for query: 509

 

[RedRaider2020]

PF angle = Cos^-1(.92)=23 Cos^-1(.67)=47.93 Cos^-1(.8)=36.86 Cos^-1(1)=0

P1 angle= Cos(PF angle - 30) and P1 angle= Cos(PF angle + 30)

Plug in all the angles and see which one gives you the answer that you're looking for.

 

[Zach Stone P.E.]

If you're looking for help with the two wattmeter method which can be really confusing, here are three videos I can suggest:

3 Steps for Solving any Two Wattmeter Method Problem Part 1 (Electrical Power PE Exam)

3 Steps for Solving any Two Wattmeter Method Problem Part 2 (Electrical Power PE Exam)

3 Steps for Solving any Two Wattmeter Method Problem Part 3 (Electrical Power PE Exam)

It goes over the theory and how to solve them. They are pretty short and to the point. They also show the phasor diagrams which are pretty helpful.

 

[Mohammed Ahmed]

Thank you all for help..