power-electronics-mcqs - Set (2)

Correct Answer: Orange && Worng Answer: Red

1. The basic elements of a electric drive is(are)-

  • (A). Electric motor
  • (B). Control system
  • (C). Electric motor and Control system
  • (D). None of the above
    • View Answer

    Explanation: Not Avilable

    2. Three phase converter are employed for :

  • (A). Large KW motors
  • (B). Small KW motors
  • (C). In all motors
  • (D). Never used
    • View Answer

    Explanation: Not Avilable

    3. A cycloconverter is :

  • (A). One stage power converter
  • (B). One stage voltage converter
  • (C). One stage frequency converter
  • (D). None of the above
    • View Answer

    Explanation: Not Avilable

    4. Which method of heating control has leading power factor ?

  • (A). Resistance heating
  • (B). Di-electric heating
  • (C). Arc heating
  • (D). Induction heating
    • View Answer

    Explanation: Not Avilable

    5. When cells of storage battery are connected in parallel, then

  • (A). Voltage increases
  • (B). Voltage decreases
  • (C). Capacity increases
  • (D). Capacity decreases
    • View Answer

    Explanation: Not Avilable

    6. A Thyristor is a :

  • (A). Four layer, three junction device
  • (B). Four layer, four junction device
  • (C). Four layer, two junction device
  • (D). Three layer, single junction device
    • View Answer

    Explanation: Not Avilable

    7. If the cathode of an SCR is made positive with respect to anode and no gate current is applied, then :

  • (A). All junctions are reverse biased
  • (B). All junctions are forward baised
  • (C). Only the middle junction is forward baised
  • (D). Only the middle junction is reverse baised
    • View Answer

    Explanation: Not Avilable

    8. Which of the following is the most suitable method to “Turn ON” thyristor :

  • (A). Gate triggering method
  • (B). dv/dt triggering method
  • (C). forward voltage triggering method
  • (D). Temperature triggering method
    • View Answer

    Explanation: Not Avilable

    9. The sink to ambient thermal resistance of SCR

  • (A). Depends on the flatness of the device
  • (B). Depends on the length of the device
  • (C). Depends on the current carrying capabiliaties
  • (D). Is independent of SCR configuration
    • View Answer

    Explanation: It does not depend on any of the device configurations.

    10. In a single-phase half-wave circuit with load RL and free-wheeling diode, the free-wheeling period is

  • (A). 0 to π
  • (B). α to π+α
  • (C). π to 2π+α
  • (D). π/2 to 2π-α
    • View Answer

    Explanation: Not Avilable

    11. A fully controlled converter uses :

  • (A). Diodes only
  • (B). Thyristor only
  • (C). Both (a) and (b)
  • (D). None of the above
    • View Answer

    Explanation: Not Avilable

    12. A three-phase full converter will require _______ number of SCRs

  • (A). 3
  • (B). 6
  • (C). 9
  • (D). 2
    • View Answer

    Explanation: Not Avilable

    13. The cycloconverter requires forced or natural commutation as under :

  • (A). Forced commutation in step-up cycloconverter
  • (B). Forced commutation in step-down cycloconverter
  • (C). Forced commutation in both step-up and step-down cycloconverter
  • (D). Natural commutation in both step-up and step-down cycloconverter
    • View Answer

    Explanation: Not Avilable

    14. A chopper is a :

  • (A). Time ratio controller
  • (B). AC to DC converter
  • (C). AC transformer
  • (D). High speed semiconductor switch
    • View Answer

    Explanation: It is a high speed on/off semiconductor switch. Note that it behaves like a DC transformer, does not mean it is a DC transformer. There is no DC transformer.

    15. In case of variable frequency system of chopper which is varied ?

  • (A). T
  • (B). Ton
  • (C). Toff
  • (D). f
    • View Answer

    Explanation: In frequency modulation scheme, the frequency (f) hence T (1/f) is varied by either keeping Ton constant or keeping Toff constant.

    16. Type-C chopper consists of :

  • (A). Two diodes and two switches
  • (B). One diode and one switch
  • (C). One diode and three switches
  • (D). Three diode and two switches
    • View Answer

    Explanation: Not Avilable

    17. Forced commutation requires :

  • (A). A pre-charged capacitor
  • (B). A pre-charged inductor
  • (C). An over damped RLC load
  • (D). A very high frequency AC source
    • View Answer

    Explanation: Not Avilable

    18. The shape of the output voltage waveform in a single pulse width modulation is :

  • (A). Square wave
  • (B). Triangular wave
  • (C). Quasi-square wave
  • (D). Sine wave
    • View Answer

    Explanation: Not Avilable

    19. Single phase half bridge inverters requires-

  • (A). Two wire AC supply
  • (B). Two wire DC supply
  • (C). Three wire AC supply
  • (D). Three wire DC supply
    • View Answer

    Explanation: Not Avilable

    20. In the series inverter control method :

  • (A). Two inverter connected back to back
  • (B). The output from the inverter is taken serial
  • (C). Output voltage of two inverters are summed up with the help of a transformer
  • (D). Output voltage of two inverters are summed up the help of a third inverter.
    • View Answer

    Explanation: Not Avilable

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