1) Harmonics in 3 phase inverters can be reduced by using
a. Passive filter
b. Active filter
c. Both passive and active filters
d. None of these
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Answer
Explanation
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ANSWER: Both passive and active filters
Explanation:
No explanation is available for this question!
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2) The advantage of using free - wheeling diode in half controlled bridge converter is that
a. There is always a path for the dc current independent of the ac line
b. There is always a path for the ac current independent of the ac line
c. There is always a path for the dc current dependent of the ac line
d. There is always a path for the ac current independent of the ac line
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Answer
Explanation
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ANSWER: There is always a path for the dc current independent of the ac line
Explanation:
No explanation is available for this question!
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3) The Graetz bridge makes excellent use of
a. Current transformer
b. Potential transformer
c. Power transformer
d. SCR
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Answer
Explanation
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ANSWER: Power transformer
Explanation:
No explanation is available for this question!
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4) If the firing angle becomes negative, then the rectifier begins to work as
a. A rectifier
b. An inverter
c. A chopper
d. A regulator
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Answer
Explanation
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ANSWER: An inverter
Explanation:
No explanation is available for this question!
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5) In a 3 phase half wave rectifier, when firing angle is less than 90 degree, then the average dc output voltage becomes
a. Positive
b. Negative
c. Zero
d. None of these
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Answer
Explanation
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ANSWER: Positive
Explanation:
No explanation is available for this question!
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6) In dual converters,
a. Both rectifiers provides positive current to the load
b. Both rectifiers provide negative current to the load
c. One rectifiers provide positive current to the load and the other negative current
d. One rectifier provide positive current to the source and the other negative current to the load
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Answer
Explanation
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ANSWER: Both rectifiers provides positive current to the load
Explanation:
No explanation is available for this question!
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7) Advantages of HVDC transmission over AC system is / are
a. Reversal of power can be controlled by firing angle
b. Very good dynamic behavior
c. They can link two AC system operating unsynchronized
d. All of these
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Answer
Explanation
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ANSWER: All of these
Explanation:
No explanation is available for this question!
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8) In a 3 phase VSI out of eight valid states, the number of valid states that produce zero ac line voltages is/are
a. One
b. two
c. Three
d. Four
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Answer
Explanation
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ANSWER: two
Explanation:
No explanation is available for this question!
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9) In a 3 phase bridge rectifier the ripple frequency is
a. Equal to the input frequency
b. Twice the input frequency
c. Three times the input frequency
d. Six times the input frequency
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Answer
Explanation
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ANSWER: Six times the input frequency
Explanation:
No explanation is available for this question!
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10) The sum of all phase current in a star connected primary winding with no neutral connection is equal to
a. Phase current
b. Three times the phase current
c. Three times the line current
d. Zero at all times
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Answer
Explanation
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ANSWER: Zero at all times
Explanation:
No explanation is available for this question!
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