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 posed to me in an interview for job.

My question comes from Advanced Problems on Measurement of Power in Polyphase Circuit in chapter Measurement of Power and Related Parameters of Electrical Measurements

Answer 1

Correct answer is (b) 0.5

To explain: 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.