1000+ Power Electronics Questions and Answers Pdf - 1

Question: 1

Germanium is not used in the fabrication of thyristors because

(A) it is much costlier than silicon

(B) it has much lower thermal conductivity than silicon

(C) its breakdown voltage is much larger than that of silicon

(D) both a and b

Ans: D

both a and b

Question: 2

The turn off time is longer than the turn on time in SCR because

(A) the forward break over voltage is high

(B) the gate pulse has been removed

(C) the anode and cathode junctions get reverse biased while gate junction is still forward biased

(D) none of the above

Ans: C

the anode and cathode junctions get reverse biased while gate junction is still forward biased

Question: 3

Practical way of obtaining static voltage equalization in series connected SCRs is by the use of

(A) one resistor across the string

(B) resistors of the same value across each SCR

(C) resistors of different values across each SCR

(D) one resistor in series with each SCR

Ans: B

resistors of the same value across each SCR

Question: 4

The nature of load current, i.e., whether load is continuous or discontinuous is controlled rectifiers

(A) does not depend on type of load and firing angle delay

(B) depends only on the firing angle delay

(C) depends only on the type of load

(D) depends both on the type of load an firing angle delay

Ans: D

depends both on the type of load an firing angle delay

Question: 5

The duration of reverse recovery transient affects which of the following aspect in a power diode?

(A) speed of response

(B) peak inverse voltage

(C) average current

(D) forward threshold voltage

Ans: B

peak inverse voltage

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