Basic Power Electronics (BPE)

Multiple Choice Questions

1   Which of the following is the application of Power Electronics?
    (A)   Fan Regulator
    (B)   Temperature controller
    (C)   Cycloconverter
    (D)   All the above

2   Which of the following is not triggering device?
    (A)   UJT
    (B)   SCR
    (C)   DIAC
    (D)   SBS

3   Long form of SCR is
    (A)   Silicon Conversion Rectifier
    (B)   Silicon Controlled Rectifier
    (C)   Selenium Controlled Rectifier
    (D)   None of the above

4   Which of the following is not Power Controlled Rectifier?
    (A)   SCR
    (B)   TRIAC
    (C)   UJT
    (D)   LASCR

5   SCR is a…..
    (A)   Four Layer Three Terminal Device
    (B)   Three Layer Four Terminal Device
    (C)   Four Layer Four Terminal Device
    (D)   Four Layer Two Terminal Device

6   TRIAC is a
    (A)   Unidirectional device
    (B)   Bidirectional Device
    (C)   Sometime Bidirectional device
    (D)   Cannot say

7   Which of the following is not part of VI characteristics of SCR?
    (A)   Forward Blocking state
    (B)   Forward Conduction state
    (C)   Saturation State
    (D)   Reverse Blocking State

8   Which of the following holds true for relationship between Holding current and Latching Current?
    (A)   Holding Current > Latching current
    (B)   Holding Current < Latching current
    (C)   Holding Current = Latching current
    (D)   Holding Current <= Latching current

9   As value of gate current through SCR increases
    (A)   Value of breakover voltage decreases
    (B)   Value of breakover voltage increases
    (C)   Value of breakover voltage remains unchanged
    (D)   None of the above

10   On state voltage drop across SCR is approximately equals to
    (A)   10 volts
    (B)   100 volts
    (C)   0.1 volt
    (D)   1 volt

11   Following symbol represents…

    (A)   DIAC
    (B)   TRIAC
    (C)   SCR
    (D)   UJT

12   Which of the following is most widely used turn on methods of SCR?
    (A)   Gate Triggering
    (B)   Light Triggering
    (C)   Forward Voltage Triggering
    (D)   dv/dt Triggering

13   Which of the following Thyristor can be turned on by light triggering?
    (A)   SCR
    (B)   TRIAC
    (C)   DIAC
    (D)   LASCR

14   Two transistor analogy of SCR can be achieved by using
    (A)   Any two-transistor choice
    (B)   Two PNP transistor
    (C)   One PNP and One NPN transistor
    (D)   One FET and One MOSFET transistor

15   For Protecting SCR from over voltage which of the following protection technique is used
    (A)   Snubber Circuit
    (B)   Inductor is connected in series
    (C)   Fuse is connected in series
    (D)   Heat sink

16   Commutation is process of
    (A)   Turning On SCR
    (B)   Turning Off SCR
    (C)   Checking SCR
    (D)   Converting SCR into TRIAC

17   Which of the following is not Forced Commutation?
    (A)   Class A commutation
    (B)   Class C commutation
    (C)   Class E commutation
    (D)   Class F commutation

18   Class C commutation is also called as
    (A)   Auxiliary Commutation
    (B)   Resonant Commutation
    (C)   Self-Commutation
    (D)   Complimentary Commutation

19   Following diagram represents which type of commutation

    (A)   Auxiliary Commutation
    (B)   Resonant Commutation
    (C)   Self-Commutation
    (D)   Complimentary commutation

20   Following symbol represents which triggering device

    (A)   UJT
    (B)   PUT
    (C)   DIAC
    (D)   SBS

21   In Forward blocking state, Junctions
    (A)   J1 – Forward Bias, J2-Forward Bias, J3- Forward Bias
    (B)   J1 – Forward Bias, J2-Forward Bias, J3- Reverse Bias
    (C)   J1 – Reverse Bias, J2-Forward Bias, J3- Reverse Bias
    (D)   None of the above

22   Role of protection circuit is
    (A)   Protect load from excess current and voltages
    (B)   Protect Source from excess current and voltages
    (C)   Protect SCR (Thyristor) from excess current and voltages
    (D)   None of the above

23   UJT exhibits …………………… in its characteristics
    (A)   Positive Resistance Region
    (B)   Negative Resistance Regio
    (C)   Non Ohmic Region
    (D)   Conductive Region

24   Long form of PUT is
    (A)   Programmable Uni Junction Transistor
    (B)   Programmable Unique Junction Thyristor
    (C)   Pointed Unit Transitory
    (D)   None of the above

25   Pulse duration in UJT relaxation oscillator is controlled by using
    (A)   R and C combination
    (B)   Restore Only
    (C)   Capacitor only
    (D)   By UJT

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