A 3-phase motor connected to a 480 V line draws 12 A with a power factor of 0.85. What is the electrical input power in kilowatts?

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Study for the Ontario Power Generation (OPG) Orange 1 Test. Ace your exam with multiple choice questions and detailed explanations. Prepare confidently!

Multiple Choice

A 3-phase motor connected to a 480 V line draws 12 A with a power factor of 0.85. What is the electrical input power in kilowatts?

Explanation:
Real input power for a balanced three-phase motor is found from P = √3 × V_L × I_L × PF, using the line-to-line voltage, line current, and power factor. Plugging in the values: V_L = 480 V, I_L = 12 A, PF = 0.85, and √3 ≈ 1.732. P ≈ 1.732 × 480 × 12 × 0.85 ≈ 9,976.32 × 0.85 ≈ 8,479.9 W ≈ 8.48 kW. This is best represented by the 8.50 kW option, since 8.48 kW rounds to 8.50 kW.

Real input power for a balanced three-phase motor is found from P = √3 × V_L × I_L × PF, using the line-to-line voltage, line current, and power factor.

Plugging in the values: V_L = 480 V, I_L = 12 A, PF = 0.85, and √3 ≈ 1.732.

P ≈ 1.732 × 480 × 12 × 0.85

≈ 9,976.32 × 0.85

≈ 8,479.9 W ≈ 8.48 kW.

This is best represented by the 8.50 kW option, since 8.48 kW rounds to 8.50 kW.

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