Wattmeter Theory And Measurement of Power - 3 - MCQs

Wattmeter Theory And Measurement of Power - 3 - MCQs

Q1. The readings of the two wattmeter used for the measurement of power input to a 3 phase induction motor are 850 W and 250 W respectively. The power factor of the motor is

A. 0.73
B. 0.76
C. 0.79
D. 0.85

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Q2. What will be the power factor of an inductive load if the reading of the two wattmeters connected to measure input power of a 3 phase induction motor is 6: 3?

A. 0.86
B. 0.89
C. 0.91
D. 0.95

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Q3. If the reading of the one wattmeter is four times the other wattmeter while measuring the input power of 3 phase induction motor then the power factor of the load will be

A. 0.56
B. 0.69
C. 0.74
D. 0.81

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Q4. In L-C connected wattmeter, compensated coil is used. The error in the wattmeter is due to power consumed by the

A. Current coil
B. Potential coil
C. Inductor
D. Capacitor

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Q5. The full scale current of a galvanometer with internal resistance of 800 ohm is 8 A. what will be the multiplying power of 80 ohm shunt with this galvanometer?

A. 8
B. 9
C. 10
D. 11

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Q6. If the reading of the two wattmeter’s is equal and opposite while measuring power in a 3 phase induction motor then the power factor of the load will be

A. Unity
B. Zero
C. 0.5 lagging
D. 0.5 leading

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Q7. During load test on 3 phase induction motor, the readings of the two wattmeters are -5.5 kW and +12.5 kW respectively. If the line voltage is 420 V then the line current will be

A. 38.91 A
B. 41.02 A
C. 42.10 A
D. 43.94 A

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Q8. The two wattmeters used for the measurement of power input read 50 kW each. What will be the readings of the two wattmeter if the power factor is changed to 0.8 leading keeping the total input power same?

A. 28.35W, 71.65W
B. 31.25W, 73.71W
C. 33.33W, 73.33W
D. 38.35W, 75.5W

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