2 Wattmeter Method Question

[Rafis]

For the wattmeter circuit below [Question from Graffeo #74], which is the truest? Per the solution the answer is (C)

But I am unable to arrive at that answer. I thought that:
W1=VAC*IA*cos(θ-30)
W2=VBC*IB*cos(θ+30)
so;
a) Check if W1=0 >>>cos(60-30)=0.86 : FALSE
b) Check if W2=0 >>>cos(-60+30)=0.86 : FALSE
c) Check if W2=0 >>>cos(-60+30)=0.86 : FALSE but W1=0 since cos(-60-30)=0 so is this a typo or am I solving this incorrectly?
d) Check if W2 is positive>>> Test θ=70 > Cos(70+30)=-0.17: FALSE since negative


So what am I doing wrong? How is C the correct answer?

 

[Zach Stone P.E.]

Hi Rafis,

There is a lot of great information on these boards already for the two-wattmeter method. If you use the search bar you'll be able to dig up plenty of prior threads that can help you with this.

In the meantime, here are my three favorite videos that I made to help engineers with the two wattmeter method for the PE exam:

Part 1 - Solving any Two Wattmeter Method Problem for the PE Exam​

Part 2 - Solving any Two Wattmeter Method Problem for the PE Exam​

Part 3 - Solving any Two Wattmeter Method Problem for the PE Exam​