2-wattmeter load power factor angle

[akyip]

Hey guys,

I have a specific question on the 2-wattmeter question. On the Eng. Pro Guides and Cram for Exam practice exams, occasionally I see this formula being used for a few 2-wattmeter questions:

Load Power factor angle theta = arctan( sqrt(3) x (Ph - Pl) / (Ph + Pl))

Where Ph is the wattmeter with the higher power reading and Pl is the wattmeter with the lower reading

How is this specific formula for the load p.f. angle derived?

The reason I ask this is that, now that the exam is transitioning to CBT, I can no longer use my Bible binder and I feel like I would have to memorize this specific formula. I would rather try to understand how to derive this formula...

Thanks for any help on this!

 

[akyip]

Guys,

After doing some more looking up, I found an article that answered my question.

For convenient reference:

https://circuitglobe.com/two-wattmeter-method-balanced-load-condition.html

 

[Zach Stone P.E.]

Hey guys,

I have a specific question on the 2-wattmeter question. On the Eng. Pro Guides and Cram for Exam practice exams, occasionally I see this formula being used for a few 2-wattmeter questions:

Load Power factor angle theta = arctan( sqrt(3) x (Ph - Pl) / (Ph + Pl))

Where Ph is the wattmeter with the higher power reading and Pl is the wattmeter with the lower reading

How is this specific formula for the load p.f. angle derived?

The reason I ask this is that, now that the exam is transitioning to CBT, I can no longer use my Bible binder and I feel like I would have to memorize this specific formula. I would rather try to understand how to derive this formula...

Thanks for any help on this!

If you're looking for a breakdown of the phasor diagram relationships these two videos sort it out: