electrical engineering MCQs – Page 236

Practise multiple-choice questions from electrical engineering for competitive examinations and subject revision. Review each marked answer and report any item that may be outdated or unclear.

electrical engineering Mcqs
1. economics of power generation2. analog electronics3. solid state switching circuits4. parallel circuits5. switchgear and protection6. op amp circuits7. transistor audio power amplifiers8. electrostatics9. heating and welding10. multi stage transistor amplifiers11. passive filters12. network theorems13. regulated d c power supply14. a c fundamentals circuits and circuit theory15. electromagnetic induction16. power electronics17. magnetism and electromagnetism18. transformers19. modulation and demodulation20. d c generators21. semiconductor theory22. single phase induction motors23. semiconductor diode24. hybrid parameters25. digital electronics26. oscillators27. earthing or grounding28. single stage transistor amplifiers29. d c motors30. transistor biasing31. amplifiers with negative feedback32. basic electrical33. electronic instruments34. synchronous motors35. field effect transistors fet36. magnetic circuit37. control systems38. industrial drives39. power generation40. series parallel circuits41. transistor tuned amplifiers42. electrical engineering materials43. rectifiers and converters44. integrated circuits45. scr silicon controlled rectifiers46. cables47. polyphase induction motors48. measurement and instrumentation49. transistors50. electrical machine design51. electrolysis and storage of batteries52. electric traction53. transmission and distribution
4701. In a 3 phase VSI out of eight valid states, the number of valid states that produce zero ac line voltages is/are_________?
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A. two

B. One

C. Four

D. Three

4702. IGBT combines the advantages of_____________?
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A. SITs and MOSFETs

B. BJTs and SITs

C. BJTs and MOSFETs

D. None of these

4703. If energy is taken from the AC side of the inverter and sends it back into the DC side, then it is known as___________?
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A. None of these

B. Motoring mode operation

C. Braking mode operation

D. Regenerative mode operation
4704. Power electronics essentially deals with control of a.c. power at____________?
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A. 50 Hz frequency

B. Frequencies above 1000 kHz

C. Frequencies less than 10 Hz

D. Frequencies above 20 kHz

4705. A step up chopper has input voltage 110 V and output voltage 150 V. The value of duty cycle is_____?
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A. 0.27

B. 0.45

C. 0.32

D. 0.67

4706. If the gate voltage of an SCR is removed, then the_______________?
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A. cathode current increases

B. anode current increases

C. anode current does not decrease at all

D. anode current decreases

4707. A GTO can be turned on by applying___________?
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A. Positive gate signal

B. Positive drain signal

C. None of these

D. Positive source signal

4708. With gate open, the maximum anode current at which SCR is turned off from ON condition is called____________?
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A. peak reverse voltage

B. breakdown voltage

C. latching current

D. holding current
4709. The conduction losses in IGBT is____________?
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A. Equal to that of MOSFET

B. More than that of MOSFET

C. Lower than that of MOSFET

D. Equal to that of BJT

4710. Which of the following is true about SIT?
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A. SIT is a high power, high frequency device

B. SIT is a low power, high frequency device

C. SIT is a high power, high voltage device

D. SIT is a high power, low frequency device

4711. Example of a voltage clamping device______________?
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A. snubber circuit

B. fast acting fuse

C. aluminium block

D. metal oxide varistor
4712. What is used to protect the SCR from over current ________________?
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A. Heat sink.

B. CB and fuse.

C. Snubber circuit.

D. Voltage clamping device.

4713. SITH is also known as___________?
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A. None of these

B. Filled controlled diode

C. Filled controlled rectifier

D. Silicon controlled rectifier

4714. A silicon controlled racitifier (SCR) is a ____________?
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A. Device with three junction

B. Unijunction device

C. Device with four junction

D. None of the above

4715. TRIAC is a semiconductor power electronic device which contains____________?
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A. Two SCRs connected in parallel

B. Two BJTs connected in series

C. Two SCRs connected in series

D. Two SCRs connected in reverse parallel
4716. In dual converters________________?
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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

4717. A Triac is a ______________?
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A. 3 terminal bidirectional switch

B. 3 terminal bilateral switch

C. 2 terminal bilateral switch

D. 2 terminal switch

4718. Delay time is defined by the interval when_______________?
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A. anode voltage drops from 100 % to 90 % of its actual value

B. all of these

C. gate current increases from 90 % to 100 % of its final value

D. anode current reaches 10 % from forward leakage current

4719. An RC snubber network used in BJT__________?
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A. Divert the collector current during turn off

B. Dissipates a fair amount of switching power

C. All of these

D. Improves the reverse bias safe operating area

4720. For an SCR gate aEUR" cathode characteristic is a straight line of 130. For triggered source volume of 15 V and allowable gate power dissipation of 0.5 W compute the gate source resistance_____?
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A. 108 I.

B. 111.9 I.

C. 11.19 I.

D. 115 I