power electronics MCQs – Page 3

Practise focused power electronics questions with marked answers for exam preparation and subject revision.

power electronics Mcqs

A. Identical to phase voltage in CSI

B. Identical to line current in VSI

C. Identical to line voltage in a VSI

D. Identical to phase voltage in VSI

42. 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

43. 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

44. 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

45. 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

46. 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

47. 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

48. 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

49. 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

50. 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

51. 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

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

B. fast acting fuse

C. aluminium block

D. metal oxide varistor

53. 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.

54. 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

55. 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

56. 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

57. 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

58. 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

59. 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

60. 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

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