1) The two wattmeters used for the measurement of power input read 50 kW each. What will be the readings of the two wattmeters 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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Answer
Explanation
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ANSWER: 28.35W, 71.65W
Explanation:
No explanation is available for this question!
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2) 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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Answer
Explanation
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ANSWER: 43.94 A
Explanation:
No explanation is available for this question!
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3) If the reading of the two wattmeters 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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Answer
Explanation
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ANSWER: Zero
Explanation:
No explanation is available for this question!
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4) 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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Answer
Explanation
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ANSWER: 11
Explanation:
No explanation is available for this question!
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5) 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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Answer
Explanation
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ANSWER: Potential coil
Explanation:
No explanation is available for this question!
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6) If the reading of 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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Answer
Explanation
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ANSWER: 0.69
Explanation:
No explanation is available for this question!
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7) 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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Answer
Explanation
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ANSWER: 0.86
Explanation:
No explanation is available for this question!
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8) 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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Answer
Explanation
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ANSWER: 0.73
Explanation:
No explanation is available for this question!
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9) A wattmeter has a pressure coil resistance of 5K ohm and current coil resistance of 0.02 ohm. What load will give equal error with the two connections if the load current is 15 A at a voltage of 240 V and 0.8 power factor.
a. 20 A
b. 24 A
c. 28 A
d. 32 A
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Answer
Explanation
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ANSWER: 24 A
Explanation:
No explanation is available for this question!
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10) The scale of induction wattmeter extends over
a. 70 degree
b. 120 degree
c. 180 degree
d. 300 degree
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Answer
Explanation
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ANSWER: 300 degree
Explanation:
No explanation is available for this question!
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