Power Electronics(Engineering > Electronics And Communication Engineering ) Questions and Answers

Question 1. The number of leads in an SCR are :
  1.    2
  2.    3
  3.    4
  4.    5
Explanation:-
Answer: Option B. -> 3
Answer: (b).3
Question 2. A thyristor has a turn on time of 6 μs. If the anode circuit is inductive, the turn on time will be
  1.    6 μs
  2.    less than 6μs
  3.    more than 6 μs
  4.    either 6 μs or less
Explanation:-
Answer: Option C. -> more than 6 μs
Answer: (c).more than 6 μs
Question 3. Assertion (A): A TRIAC is a bidirectional SCR.
Reason (R): A TRIAC is a four layers 3 terminal device and can conduct in both directions.
  1.    Both A and R are correct and R is correct explanation of A
  2.    Both A and R correct but R is not correct explanation of A
  3.    A is correct but R is wrong
  4.    A is wrong but R is correct
Explanation:-
Answer: Option A. -> Both A and R are correct and R is correct explanation of A
Answer: (a).Both A and R are correct and R is correct explanation of A
Question 4. The value of capacitor C for dynamic equalising circuit of series connected thyristors is determined by
  1.    forward characteristics of thyristors
  2.    reverse recovery characteristics of thyristors
  3.    both forward and reverse recovery characteristics of thyristors
  4.    none of the above
Explanation:-
Answer: Option B. -> reverse recovery characteristics of thyristors
Answer: (b).reverse recovery characteristics of thyristors
Question 5. The total number of leads in reverse conducting thyristor is
  1.    2
  2.    3
  3.    1
  4.    4
Explanation:-
Answer: Option B. -> 3
Answer: (b).3
Question 6. In a multiphase chopper, all choppers operate together.
  1.    True
  2.    False
  3.    May be True or False
  4.    Can't say
Explanation:-
Answer: Option B. -> False
Answer: (b).False
Question 7. Current derating may be necessary when thyristors are operating in
  1.    series
  2.    parallel
  3.    series or parallel
  4.    none of the above
Explanation:-
Answer: Option B. -> parallel
Answer: (b).parallel
Question 8. Assertion (A): The surge current which an SCR can withstand is much higher than rms on state current.
Reason (R): The duration of surge current is very small.
  1.    Both A and R are correct and R is correct explanation of A
  2.    Both A and R correct but R is not correct explanation of A
  3.    A is correct but R is wrong
  4.    A is wrong but R is correct
Explanation:-
Answer: Option A. -> Both A and R are correct and R is correct explanation of A
Answer: (a).Both A and R are correct and R is correct explanation of A
Question 9. The terminals of a power MOSFET are called
  1.    emitter, base, collector
  2.    source, gate, drain
  3.    source, base, drain
  4.    emitter, gate, drain
Explanation:-
Answer: Option B. -> source, gate, drain
Answer: (b).source, gate, drain
Question 10. If duty cycle is a and the load is α resistance R, the rms value of output voltage is
  1.    αV
  2.    √α V
  3.    α²V
  4.    αV/R
Explanation:-
Answer: Option B. -> √α V
Answer: (b).√α V
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