Page 460 - Basic Electrical Engineering

Let the ratio of wattmeter readings be X, i.e.,

and

Now we will divide both numerator and dinominator by W . Then tan ϕ will
1
be

and power factor,

Substituting

−1
or, ϕ = cos (0.866)
= 30°

W = V I cos (30° – 30°) = 400 × 10 × cos 0° =
Wattmeter reading, 1 L L
4000 W

W = V I cos (30° + 30°) = 400 × 10 × cos 60° =
2
L L
Wattmeter reading,
1000 W