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Q-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
……………
Answer: a
Explanation: During the conversion process, the current flows in both the directions, hence both inverting and converting action takes place.
Q-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
……………
Answer: b
Explanation: Reduction factor = output frequency/input frequency.
Q-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
……………
Answer: b
Explanation: The basic principle of three phase cycloconverter is to vary progressively the firing angle of the controlling devices.
Q-The single phase bridge type cycloconverter uses __________ number of SCRs.
a) 4
b) 8
c) 6
d) none of the mentioned
…………
Answer: b
Explanation: 4 negative and 4 positive SCRs are employed in bridge type cycloconverter.
Q-A cycloconverter is a _________
a) one stage power converter
b) one stage voltage converter
c) one stage frequency converter
d) none of the mentioned
………..
Answer: c
Explanation: A cycloconverter converters input power at one frequency to output power at a different frequency with one-stage conversion.
Q-Choose the incorrect statement.
a) SMPS is less sensitive to input voltage variations
b) SMPS is smaller as compared to rectifiers
c) SMPS has low input ripple
d) SMPS is a source of radio interference
………..
Answer: c
Explanation: SMPS has higher output ripple and its regulation is worse.
Q-_________ is used for critical loads where temporary power failure can cause a great deal of inconvenience.
a) SMPS
b) UPS
c) MPS
d) RCCB
…………
Answer: b
Explanation: Uninterruptible Power Supply is used where loads where temporary power failure can cause a great deal of inconvenience.
Q-Static UPS requires __________
a) only rectifier
b) only inverter
c) both inverter and rectifier
d) none of the mentioned
………..
Answer: c
Explanation: Rectifier to converter the dc from the battery to ac. Inverter to charge the battery from mains.
Q-The negative polarity is used in the monopolar link because it
a) uses less conductor size
b) is safer
c) produces less radio interference
d) has less resistance
………….
Answer: c
Explanation: The monopolar link uses just a single conductor, which is usually negative as it produces less radio interference and corona.
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