This set of Power Electronics Multiple Choice Questions & Answers (MCQs) focuses on “Cycloconverters”.
1. A cycloconverter is a _________
a) one stage power converter
b) one stage voltage converter
c) one stage frequency converter
d) none of the mentioned
View Answer
Explanation: A cycloconverter converters input power at one frequency to output power at a different frequency with one-stage conversion.
2. Applications of cycloconverters include
a) speed control of ac drives
b) induction heating
c) static VAr compensation
d) all of the mentioned
View Answer
Explanation: Speed of induction machines can be controlled by controlling the input frequency. In induction heating, eddy current is proportional to the square of input frequency.
3. The single phase mid-point type cycloconverter uses __________ number of SCRs.
a) 4
b) 8
c) 6
d) none of the mentioned
View Answer
Explanation: 2 negative and 2 positive SCRs are employed in mid-point type cycloconverter.
4. The single phase bridge type cycloconverter uses __________ number of SCRs.
a) 4
b) 8
c) 6
d) none of the mentioned
View Answer
Explanation: 4 negative and 4 positive SCRs are employed in bridge type cycloconverter.
5. In the positive half cycle from ωt = 0 to π
a) P1 and P2 are forward biased
b) N1 and P2 are forward biased
c) P1 and N2 are forward biased
d) None of the mentioned
View Answer
Explanation: In the positive half cycle, upper terminal is positive of the upper secondary and the lower terminal is negative for the lower secondary. Hence, P1 and N2 are forward biased.
6. In the below given cycloconverter circuit, _________ and _________ conduct in one cycle together.
a) P1, P2 and N1, N2
b) P1, N2 and N1, P2
c) N1, P1 and N1, P2
d) None of the mentioned
View Answer
Explanation: In the positive half cycle, upper terminal is positive of the upper secondary and the lower terminal is negative for the lower secondary. Hence, P1 and N2 are forward biased. And likewise, N1 and P2 will conduct in the next half cycle.
7. In the positive half cycle, _________ SCRs are forward biased.
a) P1, P2, N1, N2
b) P1, P2, P3, P4
c) N1, N2, N3, N4
d) P3, P4, N1, N2
View Answer
Explanation: Pairs P1, P2 and N1, N2 are forward biased from ωt = 0 to π.
8. The principle of three phase cycloconverter is to
a) add and remove number of SCRs
b) vary progressively the firing angle of the devices
c) keep the firing angle as 0° for all the devices
d) none of the mentioned
View Answer
Explanation: The basic principle of three phase cycloconverter is to vary progressively the firing angle of the controlling devices.
9. In three phase cycloconverters, the reduction factor is given by
a) input frequency/output frequency
b) (input frequency/output frequency) -1
c) (input frequency/output frequency) -1/2
d) (input frequency/output frequency) 1/2
View Answer
Explanation: Reduction factor = output frequency/input frequency.
10. In a three phase half-wave cycloconverter ___________
a) both inverting and converting action takes place
b) only inversion action takes place
c) only converting action takes place
d) none of the mentioned
View Answer
Explanation: During the conversion process, the current flows in both the directions, hence both inverting and converting action takes place.
Sanfoundry Global Education & Learning Series – Power Electronics.
To practice all areas of Power Electronics, here is complete set of 1000+ Multiple Choice Questions and Answers.
