Electrician Red Seal · Question
A 600 V, 3-phase induction motor with a nameplate FLA of 50 A is being tested. Using a clamp-on ammeter, a technician measures the current on one phase at 40 A under a specific load condition. If the motor's power factor is 0.85 and its efficiency is 90% at this load, what is the approximate real power consumed by the motor in kilowatts (kW)?
The real power (P) for a 3-phase motor is calculated as P = √3 × V_L × I_L × PF. So, P = √3 × 600 V × 40 A × 0.85 ≈ 35398 W. In kilowatts, this is approximately
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Question: A 600 V, 3-phase induction motor with a nameplate FLA of 50 A is being tested. Using a clamp-on ammeter, a technician measures the current on one phase at 40 A under a specific load condition. If the motor's power factor is 0.85 and its efficiency is 90% at this load, what is the approximate real power consumed by the motor in kilowatts (kW)?
Answer options:
- 24.9 kW ✅ 35.4 kW
- 42.5 kW
- 49.9 kW
Correct answer: 35.4 kW
Explanation: The real power (P) for a 3-phase motor is calculated as P = √3 × V_L × I_L × PF. So, P = √3 × 600 V × 40 A × 0.85 ≈ 35398 W. In kilowatts, this is approximately 35.4 kW. Efficiency is for mechanical output, not electrical input, and FLA is the full load current, not actual measured current.
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