Rectifiers

1. On which of the following factors the number of phases for which a rectifier should be designed depend?

1. The voltage regulation of the rec¬tifier should be low
2. In the output circuit there should be no harmonics
3. The power factor of the system should be high
4. The rectifier supply transformer should be utilized to the best ad-vantage
5. all of the above

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2. In a phase-shift control method, the phase shift between anode and grid voltages can be achieved by means of

1. shunt motor
2. synchronous motor
3. induction regulator
4. synchronous generator

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3. A commutating rectifier consists of commutator driven by

1. an induction motor
2. a synchronous motor
3. a D.C. series motor
4. a D.C. shunt motor

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4. A mercury arc rectifier possesses _________ regulation characteristics

1. straight line
2. curved line
3. exponential
4. none of the above

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5. A rotary converter combines the function of

1. an induction motor and a D.C. generator
2. a synchronous motor and a D.C. generator.
3. a D.C. series motor and a D.C. generator
4. none of the above

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6. A rotary converter in general construction and design, is more or less like

1. a transformer
2. an induction motor
3. an alternator
4. any D.C. machine

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7. A rotary converter is a single machine with

1. one armature and one field
2. two armatures and one field
3. one armature and two fields
4. none of the above

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8. A rotary converter operates at a

1. low power factor
2. high power factor
3. zero power factor
4. none of the above

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9. A synchronous converter can be started

1. by means of a small auxiliary motor
2. from AC. side as induction motor
3. from D.C. side as D.C. motor
4. any of the above methods

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10. Ageing of a selenium rectifier may change the output voltage by

1. 5 to 10 per cent
2. 15 to 20 per cent
3. 25 to 30 per cent
4. none of the above

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