1. The function of bleeder resistance in filter circuits is that
a) to maintain minimum current necessary for optimum inductor filter operation.
b) to work as voltage divider in order to provide variable output from the supply.
c) to provide discharge path to capacitors so that output becomes zero when the circuit has been de-energized
d) All of these
ans. d
2. In a 3-phase half wave rectifier, each diode conducts for a duration of
a) 180 degrees
b) 30 degrees
c) 60 degrees
d) 45 degrees
ans. c
3. Ripple frequency of a 6-phase half-wave rectifier for 230 V, 50 Hz input will be
a) 150 Hz
b) 50 Hz
c) 300 Hz
d) 100 Hz
ans. c
4. As the number of phases in a multi-phase rectifier are increased the output will
a) increase
b) become more smooth
c) decrease
d) the diodes will require high peak inverse voltage
ans. b
5. For a rectifier output of 150 kW at 500 V , an average current rating of 50 A for each diode is sufficient in
a) 3-phase full wave rectifier
b) 6-phase half wave rectifier
c) 3-phase half waver rectifier
d) none of these
ans. b
6. The effect of DC saturation in a rectifier transformer is
a) to decrease the output
b) to increase the output
c) to decrease the ac components of the output
d) none of these
ans. a
7. In a 3-phase half wave rectifier, the output voltage is equal to
a) the most positive in phase voltage at any instant
b) the difference of most positive and most negative input phases at any instant
c) the average value of the three phases.
d) the difference of the two positive phase voltages
ans. a
8. In a 3-phase half wave rectifier, if the input phase voltage is 200 V, the PIV required for each diode will be
a) 400 V
b) 346 V
c) 370 V
d) 200 V
ans. c
9. The rectifier , which requires minimum amount of filtering is
a) half wave rectifier
b) full wave rectifier
c) voltage doubler circuit
d) SCR half-wave rectifier
ans. d
10. A capacitor of 100 µF is charged to 10 V through a resistance of 10 K . It will be fully charged in
a) 5 sec
b) 0.1 sec
c) 1 sec
d) 0.5 sec
ans. a
a) to maintain minimum current necessary for optimum inductor filter operation.
b) to work as voltage divider in order to provide variable output from the supply.
c) to provide discharge path to capacitors so that output becomes zero when the circuit has been de-energized
d) All of these
ans. d
2. In a 3-phase half wave rectifier, each diode conducts for a duration of
a) 180 degrees
b) 30 degrees
c) 60 degrees
d) 45 degrees
ans. c
3. Ripple frequency of a 6-phase half-wave rectifier for 230 V, 50 Hz input will be
a) 150 Hz
b) 50 Hz
c) 300 Hz
d) 100 Hz
ans. c
4. As the number of phases in a multi-phase rectifier are increased the output will
a) increase
b) become more smooth
c) decrease
d) the diodes will require high peak inverse voltage
ans. b
5. For a rectifier output of 150 kW at 500 V , an average current rating of 50 A for each diode is sufficient in
a) 3-phase full wave rectifier
b) 6-phase half wave rectifier
c) 3-phase half waver rectifier
d) none of these
ans. b
6. The effect of DC saturation in a rectifier transformer is
a) to decrease the output
b) to increase the output
c) to decrease the ac components of the output
d) none of these
ans. a
7. In a 3-phase half wave rectifier, the output voltage is equal to
a) the most positive in phase voltage at any instant
b) the difference of most positive and most negative input phases at any instant
c) the average value of the three phases.
d) the difference of the two positive phase voltages
ans. a
8. In a 3-phase half wave rectifier, if the input phase voltage is 200 V, the PIV required for each diode will be
a) 400 V
b) 346 V
c) 370 V
d) 200 V
ans. c
9. The rectifier , which requires minimum amount of filtering is
a) half wave rectifier
b) full wave rectifier
c) voltage doubler circuit
d) SCR half-wave rectifier
ans. d
10. A capacitor of 100 µF is charged to 10 V through a resistance of 10 K . It will be fully charged in
a) 5 sec
b) 0.1 sec
c) 1 sec
d) 0.5 sec
ans. a
