A three-phase motor connected to a 480 V supply draws 12 A with a power factor of 0.8. What is the input real power?

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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 three-phase motor connected to a 480 V supply draws 12 A with a power factor of 0.8. What is the input real power?

Explanation:
For a balanced three-phase motor, input real power is calculated using P = √3 × V_line × I_line × cos φ. Here, the line voltage is 480 V, the line current is 12 A, and the power factor is 0.8. Compute √3 × 480 × 12 ≈ 1.732 × 480 × 12 ≈ 9,976 W. Multiply by cos φ: 9,976 × 0.8 ≈ 7,981 W, which is about 7.98 kW. This matches the given answer.

For a balanced three-phase motor, input real power is calculated using P = √3 × V_line × I_line × cos φ. Here, the line voltage is 480 V, the line current is 12 A, and the power factor is 0.8. Compute √3 × 480 × 12 ≈ 1.732 × 480 × 12 ≈ 9,976 W. Multiply by cos φ: 9,976 × 0.8 ≈ 7,981 W, which is about 7.98 kW. This matches the given answer.

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