Electronics and Communication Engineering - Power Electronics

21. 

In a modified series inverter

A. the maximum output frequency is less than frequency of damped oscillations
B. the output frequency can be even higher than the frequency of damped oscillations
C. the output frequency cannot exceed the frequency of damped oscillations
D. any of the above

Answer: Option B

Explanation:

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22. 

Assertion (A): Light triggering is very suitable for HVDC transmission.

Reason (R): Light triggering has the advantage of complete electrical isolation of gate circuit.

A. Both A and R are correct and R is correct explanation of A
B. Both A and R correct but R is not correct explanation of A
C. A is correct but R is wrong
D. A is wrong but R is correct

Answer: Option A

Explanation:

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23. 

Class A and class B chopper

A. operate in first quadrant
B. operate in second quadrant
C. class A chopper operates in first quadrant while class B operates in second quadrant
D. may operate in either first or second quadrant

Answer: Option C

Explanation:

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24. 

To turn off an SCR, it is necessary to reduce its current to less than :

A. trigger current
B. holding current
C. breakover current
D. none of the above

Answer: Option B

Explanation:

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25. 

When a single phase dual converter is operating in circulating current mode

A. both converters are working as rectifiers simultaneously
B. one converter is always working as rectifier and the other as inverter
C. only one converter is working at one time
D. both converters are either working as rectifiers or as inverters simultaneously

Answer: Option B

Explanation:

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