Thursday, December 27, 2012

Power Electronics MCQ Objectives

1. An IGBT has three terminals called:
a) Collector, Emitter and Base
b) Drain, Source and Base
c) Drain, Source and Gate
d) Collector, Emitter and Gate

2. The function of snubber circuit connected across the SCR is to:
a) Suppress dv/dt
b) Increase dv/dt
c) Decrease dv/dt
d) Decrease di/dt

3. An UJT exhibits negative resistance region:
a) Before the break point
b) Between peak and valley point
c) After the valley point
d) Both (a) and (c)

4. For dynamic equalizing circuit used for series connected SCRs, the choice of C is based on:
a) Reverse recovery characteristics
b) Turn-on characteristics
c) Turn-off characteristics
d) Rise time characteristics

5. A four quadrant operation require:
a) Two full converters in series
b) Two full converters connected back to back
c) Two full converters connected in parallel
d) Two semi conductors connected back to back 

6. In a circulating-current type of dual converter, the nature of the voltage across the reactor is:
a) Alternating
b) Pulsating
c) Direct
d) Triangular

7. The frequency of the ripple in the output voltage of 3-phase semiconductor depends on:
a) Firing angle and load resistance
b) Firing angle and load inductance
c) The load circuit parameters
d) Firing angle and the supply frequency

8. A single-phase full bridge inverter can operate in load-commutation mode in case load consists of:
a) RL load
b) RLC underdamped
c) RLC damped
d) RLC critically damped

9. Practical way of obtaining static voltage equalization in series connected SCRs is by the use of:
a)  One resistor across the string
b) Resistors of different values across each SCR
c) Resistors of the same value across each SCR
d) One resistor in series with each SCR

10. A resistor connected across the gate and cathode of an SCR in a circuit increases its
a) dv/dt rating
b) Holding current
c) Noise Immunity
d) Turn-off time


Post a Comment