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.Management Sciences
Category: Rectifiers and Converters
Which of the following methods may be used to convert A.C. system to D.C ?
A. Rectifiers
B. Motor converters
C. Motor-generator sets
D. Rotary converters
E. All of the above
Which of the following AC. motors is usually used in large motor-generator sets?
A. Synchronous motor
B. Squirrel cage induction motor
C. Slip ring induction motor
D. Any of the above
On which of the following factors the number of phases for which a rectifier should be designed depend ?
A. The voltage regulation of the rec¬tifier should be low
B. In the output circuit there should be no harmonics
C. The power factor of the system should be high
D. The rectifier supply transformer should be utilized to the best ad-vantage
E. all of the above
In a rotary converter I2R losses as compared to a D.C. generator of the same size will be___________?
A. same
B. less
C. double
D. three times
The efficiency of the copper oxide rectifier seldom exceeds____________?
A. 90 to 95%
B. 85 to 90%
C. 80 to 85%
D. 65 to 75%
In a mercury arc rectifier, the anode is usually made of_____________?
A. copper
B. aluminium
C. silver
D. graphite
E. tungsten
Normally, which of the following is used, when a large-scale conversion from AC. to D.C. power is required ?
A. Motor-generator set
B. Motor converter
C. Rotary converter
D. Mercury arc rectifier
To produce cathode spot in a mercury arc rectifier______________?
A. anode is heated
B. tube is evacuated
C. an auxiliary electrode is used
D. low mercury vapour pressures are used
Which of the following metals is generally manufactured by electrolysis process ?
A. Load
B. Aluminium
C. Copper
D. Zinc
E. None of the above
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