page 1 | Power Electronics and Drives MCQ

Q11. When thyristor and transistor as a switch are compared, the true statement is

Thyristor requires turns off circuit while transistor does not

The voltage drop of the thyristor is less than transistor

Thyristor requires a continuous gate current

Transistor does not draw continuously base current

Q12. Which speed control method is perferred for constant torque drive?

Field control

Armature voltage control

Mechanical loading system

None of the above

Q13. If a diode is connected anti-parallel with a thyristor then

both turn-off losses and turn-off time decreases

turn-off power loss decreases but turn-off time increases

turn-off power loss increases but turn-off time decreases

none of the above

Q14. 3 - phase voltage source inverter is operated in 180° conduction mode. Which one of the following statements is true?

Both pole-voltage and line-voltage will have 3rd harmonic components

Pole-voltage will have 3rd harmonic component but line-voltage will be free from 3rd harmonic

Line-voltage will have 3rd harmonic component but pole-voltage will be free from 3rd harmonic

Both pole-voltage and line-voltage will be free from 3rd harmonic components

Q15. The most common Gate triggering signal is

A short duration pulse

A high frequency pulse for train

A low frequency pulse train

None of the above

Q16. The duty cycle of a step down chopper is

\(T_{on} / (T_{on} + T_{off})\)

\(T_{off} / (T_{on} + T_{off})\)

\((T_{on} + T_{off}) / T_{on}\)

\(T_{on} + T_{off}) / T_{off}\)

Q17. Which of the following is used as an active device in electronics circuits?

Transformer

Electric Heater

SCR

Loud speaker

Q18. MOSFET are suitably used were

Latching characteristics required

frequency is comparatively high

Both A & B

none of the above

Q19. The threshold voltage of an n-channel MOSFET can be increased by

increasing the channel doping

reducing the channel length

reducing gate oxide thickness

decreasing the channel doping concentration

Q20. The figure shown above represents construction of which of the following?

Diode

Transistor

MOSFET

SCR

MCQ

POWER ELECTRONICS & DRIVES