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A 460-V 60-Hz four-pole Y-connected induction motor is rated at 25 hp. The equivalent circuit parameters are R1 = 0.15 Ω, R2 = 0.154 Ω, XM = 20 Ω, X1 = 0.852 Ω, and X2 = 1.066 Ω.

The rotor power factor is found using θ = tan-1(X2/R2/s) = tan-1(1.066/7.7) = 7.88° and PF = cos(7.88°) = 0.991 and is stated to be lagging.

Why is the power factor lagging and not leading? I thought if the angle was positive, the power factor is leading.

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Motor inductance basics current ALWAYS lags voltage. PF is only negative when operated as a generator.

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As to why, the rotor current is induced BY the stator current. So when acting as a motor, it is ALWAYS going to be taking place AFTER the stator induces it. Power Factor is just the measurement of that lag.

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