POWER ELECTRONICS AND DRIVES PART 18

POWER ELECTRONICS AND DRIVES PART 18

1. In the ___________ type of chopper, two stage conversions takes place.
a) AC-DC
b) AC link
c) DC link
d) None of the mentioned


Answer: b

2. Choppers converter
a) AC to DC
b) DC to AC
c) DC to DC
d) AC to AC
 
Answer: c
3. A chopper may be thought as a
a) Inverter with DC input
b) DC equivalent of an AC transformer
c) Diode rectifier
d) DC equivalent of an induction motor
 
Answer: b
 

4. Which device can be used in a chopper circuit?
a) BJT
b) MOSFET
c) GTO
d) All of the mentioned
 

Answer: d

5. A chopper is a
a) Time ratio controller
b) AC to DC converter
c) DC transformer
d) High speed semiconductor switch
 

Answer: d

6. What is the duty cycle of a chopper ?
a) Ton/Toff
b) Ton/T
c) T/Ton
d) Toff x Ton
 

Answer: b

7. The load voltage of a chopper can be controlled by varying the
a) duty cycle
b) firing angle
c) reactor position
d) extinction angle
 

Answer: a

8. The values of duty cycle (α) lies between
a) 0<α<1
b) 0>α>-1
c) 0<=α<=1
d) 1<α<100
 

Answer: c
9. If T is the time period for a chopper circuit and α is its duty cycle, then the chopping frequency is
a) Ton/α
b) Toff/α
c) α/Toff
d) α/Ton
 

Answer: d

10. Find the output voltage expression for a step down chopper with Vs as the input voltage and α as the duty cycle.
a) Vo = Vs/α
b) Vo = Vs x α
c) Vo = Vs2/α
d) Vo = 2Vs/απ
 

Answer: b