Power Electronics MCQ Questions & Answers

21

An SCR remains turned on if the anode current is more than the

A) Breakdown current B) Trigger current C) Holding current D) Threshold current

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Answer & Solution

Answer: Option C

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22

Calculate the power factor of a single-phase thyristor-controlled bridge rectifier if the firing angle is 30°.

A) 0.686 B) 0.866 C) 0.78 D) 0.9

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Answer & Solution

Answer: Option C

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23

An incremental model of a solid state device is one which represents the

A) ac property of the device at the desired operating point B) dc property of the device at all operating points C) complete ac and dc behaviour of the device at all operating points D) ac property of the device at all operating points

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Answer & Solution

Answer: Option A

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24

Which of the following thyristors can be used for high frequency of operation?

A) TRIAC B) DIAC C) SCR D) GTO

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Answer & Solution

Answer: Option D

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25

For harmonic distortion reading of D₂ = 0.1, D₃ = 0.02 and D₄ = 0.01, with I₁ = 4 A and R_C = 8 Ω, calculate the total harmonic distortion (THD) fundamental power component (P₁), and total power (P).

A) THD = 0.1; P₁ = 64 W and P = 64.64 W B) THD = 0.2; P₁ = 32 W and P = 32.32 W C) THD = 0.1; P₁ = 32 W and P = 32.32 W D) THE = 0.2; P₁ = 64 W and P = 64.32 W

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Answer & Solution

Answer: Option A

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26

The ON voltage and forward break over voltage of an SCR depend on the

A) gate current alone B) bandgap of the semiconductor alone C) gate current and the semiconductor bandgap respectively D) semiconductor bandgap and the gate current respectively

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Answer & Solution

Answer: Option C

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27

Once the SCR starts conducting a forward current, its gate loses control over

A) Anode circuit voltage only B) Anode circuit current only C) Anode circuit current and voltage D) Anode circuit current, voltage and time

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Answer & Solution

Answer: Option C

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28

A High speed digital subsystem requires three voltages V₁, V₂ and V₃ with 1 : 2 : 1 power ratings, respectively. The power supply is designed with the distribute power conversion scheme as shown in the following figure. What is the overall power conversion efficiency?
Power Electronics mcq question image

A) $$\frac{{4 \times {\eta _1} \times {\eta _2} \times {\eta _3}}}{{{\eta _2}{\eta _3} + 2 \times {\eta _3} + {\eta _2}}}$$ B) $$\frac{{{\eta _1} \times {\eta _2} \times {\eta _3}}}{{{\eta _2}{\eta _3} + 2 \times {\eta _3} + {\eta _2}}}$$ C) $$\frac{{4 \times {\eta _1} \times {\eta _2} \times {\eta _3}}}{{{\eta _2}{\eta _3} + {\eta _2} + {\eta _3}}}$$ D) $$\frac{{2 \times {\eta _1} \times {\eta _2} \times {\eta _3}}}{{{\eta _2}{\eta _3} + {\eta _2} + {\eta _3}}}$$

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Answer & Solution

Answer: Option A

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29

DC choppers belong to the category of,

A) DC - DC converter B) AC - DC converter C) Inverter D) AC - AC converter

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Answer & Solution

Answer: Option A

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30

A Triac has three terminals viz . . . . . . . .

A) Drain, source, gate B) Two main terminal and a gate terminal C) Cathode, anode, gate D) None of the above

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Answer & Solution

Answer: Option B

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Power Electronics MCQ Questions & Answers | ECE