rectifiers and converters MCQs – Page 3

Practise focused rectifiers and converters questions with marked answers for exam preparation and subject revision.

rectifiers and converters Mcqs

41. In a rotary converter armature currents are______________?
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A. a.c. only

B. d.c. only

C. partly a.c. and partly d.c.

42. When a rectifier is loaded which of the following voltage drops take place ?
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A. Arc voltage drop

B. All of the above

C. Voltage drop in resistance of transformer and smoothing chokes

D. Voltage drop in transformer reactance

43. In a mercury arc rectifier positive ions are attracted towards______________?
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A. mercury pool

B. shell bottom

C. anode

D. cathode

44. The voltage drop at anode, in a mercury arc rectifier is due to_____________?
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A. high ionization potential

B. self restoring property of mercury

C. energy spent in overcoming the electrostatic field

D. high temperature inside the rectifier

45. Which of the following methods may be used to convert A.C. system to D.C ?
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A. Motor-generator sets

B. Rotary converters

C. All of the above

D. Rectifiers

E. Motor converters

46. Which of the following is reversible in action ?
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A. Rotary converter

B. Any of the above

C. None of the above

D. Motor generator set

E. Motor converter

47. A synchronous converter can be started______________?
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A. from AC. side as induction motor

B. from D.C. side as D.C. motor

C. by means of a small auxiliary motor

D. any of the above methods

E. none of the above methods

48. A rotary converter is a single machine with______________?
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A. one armature and one field

B. two armatures and one field

C. one armature and two fields

D. none of the above

49. In phase-shift control method the control is carried out by varying the of grid voltage
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A. none of the above

B. phase

C. any of the above

D. magnitude

E. polarity

50. The potential drop in the arc, in a mercury arc rectifier, varies_____________?
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A. 0.05 V to 0.2 V per cm length of the arc

B. 2 V to 3.5 V per cm length of the arc

C. none of the above

D. 0.5 V to 1.5 V per cm length of the arc

51. The ignited or auxiliary anode in mercury arc rectifier is made of____________?
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A. aluminium

B. copper

C. graphite

D. boron carbide

52. Which of the following mercury arc rectifier will deliver least undulating current?
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A. Three-phase

B. Two-phase

C. Six-phase

D. Single-phase

53. The metal rectifiers are preferred to valve rectifiers due to which of the following advantages ?
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A. They are mechanically strong

B. They do not require any voltage for filament heating

C. Both (A) and (B)

D. None of the above

54. In selenium rectifiers efficiencies ranging from _______ to _______ percent are attainable?
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A. 25, 35

B. 40, 50

C. 60, 70

D. 75, 85

55. The voltage drop between the anode and cathode, of a mercury arc rectifier comprises of the following_____________?
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A. anode drop, cathode drop and arc drop

B. anode drop and cathode drop

C. anode drop and arc drop

D. cathode drop and arc drop

56. Copper oxide rectifier is usually designed not to operate above___________?
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A. 20C

B. 30C

C. 10C

D. 45C

57. Which of the following metals is generally manufactured by electrolysis process ?
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A. Copper

B. Zinc

C. Aluminium

D. None of the above

E. Load

58. In a phase-shift control method, the phase shift between anode and grid voltages can be achieved by means of______________?
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A. synchronous generator

B. induction regulator

C. synchronous motor

D. shunt motor

Showing 41 to 58 of 58 mcqs