Top 250+ Solved Power Electronics MCQ Questions Answer
Q. The sum of all phase current in a star connected primary winding with noneutral connection is equal to
a. Phase current
b. Three times the phase current
c. Three times the line current
d. Zero at all times
Q. In a 3 phase bridge rectifier the ripple frequency is
a. Equal to the input frequency
b. Twice the input frequency
c. Three times the input frequency
d. Six times the input frequency
Q. As the breakdown voltage reached, the DIAC exhibits
a. Negative resistance characteristics
b. Goes into avalanche condition
c. Voltage drop snaps back
d. All of these
Q. In BJT, the forward biased base emitter junction inject holes from base toemitter, the holes
a. Do not contribute to the collector current
b. Result in net current flow component into the base
c. Contribute to the collector current
d. Only (a) and (b)
Q. In BJT, switching losses occurs
a. Only at turn - on
b. Only at turn - off
c. Both at turn on and off
d. None of these
Q. Choppers is a
a. AC - DC converters
b. AC - AC converters
c. DC - AC converters
d. DC - DC converters
Q. The average value of the output voltage in a step - down dc chopper is givenby
a. V 0 = V s
b. V 0 = D V s
c. V 0 = V s / D
d. V 0 = V s / ( 1 - D )
Q. For 3 phase rotary converters, when power factor is unity. the ac line to dccurrent ratio is
a. 1.5
b. 1.1
c. 1.0
d. 0.942.
Q. In an arc rectifier the drop in voltage at the cathode is approximately
a. 1 volt
b. 6 to 7 volts
c. 60 to 70 volts
d. 1.2 V7 volts.
Q. In arc rectifiers mercury is chosen as the liquid for rectifier because
a. it has low specific heat
b. it has low ionization potential
c. it has high atomic weight
d. all of the above.