If the reading of two wattmeters are equal and positive in two wattmeter method, the load power factor in abalanced 3-phase 3-wire circuit will be

• A. 0.5
• B. 0.866
• C. zero
• D. unity

Answer: (D)

W1 = W2 (+Ve) → PF = 1
W1, W2 Positive → PF > 0.5
W1 +Ve, W2 = 0 → PF = 0.5
W1 +Ve, W2 = -Ve → PF < 0.5
W1 = - W2 → PF = 0