# Power Factor Basics for the PE Exam, Phasor Diagrams and Power Triangles and Unity Power Factor (PF = 1)



## Zach Stone P.E. (Jun 15, 2020)

Most engineers already know that power factor (PF) is the cosine of the power angle (θ).

But did you know that the power angle (θ) actually comes from the phase angle of the total connected impedance (Z)?









This is a small detail that most engineers miss while studying for the PE exam that can result in incorrect answers and a lower overall exam score, making it harder to reach the passing "cut score" of the PE exam.

To help you understand why the power angle (θ) is actually the circuit impedance angle (θz), I'll teach you all the tricks and shortcuts you'll need to quickly calculate the power factor (PF) of a circuit. 

I'll also explain all of the subtle details that power factor can tell us about a circuit such as the relationships between:

Voltage (V) and current (I)

Reactance (X) and resistance (R)

Real power (P) and apparent power |S|

Complex power (S) and reactive power (Q)

 I'll also talk to you about the special conditions that exist during unity power factor such as:

Why the power triangle no longer looks like a triangle

Why the apparent power |S| and real power (P) are identical even though the units are different (VA and W)

Why the reactive power (Q) will equal zero VAR

Why the reactance (X) will equal zero ohms





*If you'd like to print the contents of the video, including all of the diagrams, graphs, and formulas, head over to the full length article:*

Electrical PE Review - Power Factor Basics for the PE Exam, Phasor Diagrams and Power Triangles Explained





I promise that even if you're well familiar with power factor (PF), you'll still learn a new new trick or two.


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