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Two-wattmeter method measures 3-phase power. Total power:
AW1 × W2
BAlgebraic sum: P = W1 + W2 (regardless of pf)
CJust W1
DW1 + W2
Answer & Solution
Correct answer: B. Algebraic sum: P = W1 + W2 (regardless of pf)
Two-wattmeter method: connect 2 wattmeters to any two lines (current coil) and remaining line (potential coil). Algebraic sum gives total 3-phase power. Works for any balance/unbalance. tan φ = √3(W1-W2)/(W1+W2) gives load power factor.
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