While measuring power of a three-phase balanced load by

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While measuring power of a three-phase balanced load by the two-wattmeter method, the readings are 100 W and 250 W. The power factor of the load is _________.

1. 1 to 10
2. 20 to 25
3. 0.78 to 0.82
4. 0.11 to 0.25

Correct Option: C

Power factor,

Cos φ = cos tan^-1		√3\|W₁ - W₂\|
		W₁ + W₂

= cos tan^-1		√3(250 - 100)
		250 + 100

cos tan^–1 [0.742]0
= 0.802 lagging.