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A three-phase motor can be regarded as a balanced Y-load. A three-phase motor draws 5.6 kW, when the line voltage is 220 V and the line current is 18.2 A. What is the power factor of the motor ?

A three-phase motor can be regarded as a balanced Y-load. A three-phase motor draws 5.6 kW, when the line voltage is 220 V and the line current is 18.2 A. What is the power factor of the motor ? Correct Answer 0.8075

Power in a three-phase system:

The power in a balanced three-phase system (for both star and delta connected) is,

Active power (P) = √3 VLIL cos ϕ

Reactive power (Q) = √3 VLIL sin ϕ

Apparent power (S) = √3 VLIL

Calculation:

Given that,

Voltage (VL) = 220 V

Line current (IL) = 18.2 A

Active Power (P) = 5.6 kW

5.6 × 1000 = √3 × 220 × 18.2 × cos ϕ 

Power Factor (cos ϕ) = .8075

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