The power factor of a single phase load can be calculated if the instruments available are_____________?
Correct answer: B. one voltmeter, one ammeter and one wattmeter
- A. one voltmeter and one ammeter
- B. one voltmeter, one ammeter and one wattmeter
- C. one voltmeter, one ammeter and one energy meter
- D. any of the above
Explanation
Power factor is calculated from cos φ = P/(VI), so voltage, current, and true power are required. A voltmeter, ammeter, and wattmeter directly provide these three quantities; voltage and current alone cannot determine power factor.
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