Question

In the Two wattmeter method of measuring power in a balanced three-phase circuit, one wattmeter shows zero and the other positive maximum. The load power factor is ___________

(a) 0

(b) 0.5

(c) 0.866

(d) 1.0

This question was addressed to me during an interview.

My doubt stems from Problems Involving Coupling Coefficient in division Resonance & Magnetically Coupled Circuit of Network Theory

Answer 1

Correct choice is (b) 0.5

To explain I would say: The load power factor is = 0.5. Since at this power factor one wattmeter shows zero and the other shows a positive maximum value of power.