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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 _________
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- 0.5
- 0.2
- 1.2
- 1.5
Correct Option: A
The wattmeters reading is proportional to cos (30 + φ)
Then other is proportional cos (30 – φ)
Thus whenever load p.f. angle φ becomes 60°, one of the wattmeters would read zero.
Hence for the given condition load load
p.ƒ = cos 60° = 0.5
