electrical engineering MCQs – Page 299

Practise multiple-choice questions from electrical engineering for competitive examinations and subject revision. Review each marked answer and report any item that may be outdated or unclear.

electrical engineering Mcqs
1. economics of power generation2. analog electronics3. solid state switching circuits4. parallel circuits5. switchgear and protection6. op amp circuits7. transistor audio power amplifiers8. electrostatics9. heating and welding10. multi stage transistor amplifiers11. passive filters12. network theorems13. regulated d c power supply14. a c fundamentals circuits and circuit theory15. electromagnetic induction16. power electronics17. magnetism and electromagnetism18. transformers19. modulation and demodulation20. d c generators21. semiconductor theory22. single phase induction motors23. semiconductor diode24. hybrid parameters25. digital electronics26. oscillators27. earthing or grounding28. single stage transistor amplifiers29. d c motors30. transistor biasing31. amplifiers with negative feedback32. basic electrical33. electronic instruments34. synchronous motors35. field effect transistors fet36. magnetic circuit37. control systems38. industrial drives39. power generation40. series parallel circuits41. transistor tuned amplifiers42. electrical engineering materials43. rectifiers and converters44. integrated circuits45. scr silicon controlled rectifiers46. cables47. polyphase induction motors48. measurement and instrumentation49. transistors50. electrical machine design51. electrolysis and storage of batteries52. electric traction53. transmission and distribution
5961. The maximum speed variation in a 3-phase synchronous motor is____________?
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A. 10 per cent

B. 4 per cent

C. 6 per cent

D. 2. per cent

E. zero
5962. For V-curves for a synchronous motor the graph is drawn between:_______________?
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A. armature current and power factor

B. power factor and field current

C. terminal voltage and load factor

D. field current and armature current
5963. If in a synchronous motor, driving mechanical load and drawing current at lagging power factor from constant voltage supply, its field excitation is increased, then its power factor__________?
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A. none of the above

B. become more

C. become less

D. remain constant

5964. An over-excited synchronous motor takes__________?
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A. leading current

B. lagging current

C. both A. and (b)

D. none of the above

5965. Slip-rings in a synchronous motor carry____________?
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A. no current

B. direct current

C. alternating current

D. all of the above

5966. Which of the following motors will be used in electric clocks?
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A. D.C. series motor

B. A.C. induction motor

C. A.C. synchronous motor

D. D.C. shunt motor

5967. Hunting in a synchronous motor cannot be due to___________?
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A. variable frequency

B. variable supply voltage

C. windage friction

D. variable load

5968. When the voltage applied to a synchronous motor is increased, which of the following will reduce?
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A. Stator flux

B. Pull in torque

C. Both A. and (b)

D. None of the above
5969. A synchronous motor can be made self starting by providing?
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A. damper winding on rotor poles

B. damper winding on stator as well as rotor poles

C. damper winding on stator

D. none of the above
5970. The operating speed of a synchronous motor can be changed to new fixed value by___________?
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A. changing the load

B. using brakes

C. changing frequency

D. changing the supply voltage

5971. A synchronous motor connected to infinite bus-bars has at constant full load, 100% excitation and unity power factor. On changing the excitation only, the armature current will have_____________?
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A. lagging power factor with over-excitation

B. leading power factor with over-excitation

C. leading power factor with under-excitation

D. no change of power factor

5972. The angle between the rotating stator flux and rotor poles is called _________ angle.
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A. torque

B. obtuse

C. power factor

D. synchronizing

5973. In a synchronous motor, damper windings are provided on____________?
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A. rotor shaft

B. none of the above

C. pole faces

D. stator frame

5974. An over excited synchronous motor is used for____________?
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A. variable speed loads

B. low torque loads

C. power factor corrections

D. fluctuating loads

5975. While starting a synchronous motor by induction motor action, field winding is usually_____________?
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A. kept open-circuited

B. connected to D.C. supply

C. short-circuited by low resistance

D. none of the above

5976. When V is the applied voltage, then the breakdown torque of a synchronous motor varies as_________?
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A. V

B. V2

C. 1/V

D. V312

5977. The shaft of synchronous motor is made of____________?
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A. alnico

B. mild steel

C. stainless steel

D. chrome steel

5978. When a 3-phase synchronous generator is supplying a zero power factor lagging load, the armature field affects the main field in the following way
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A. augments it directly

B. none of the above

C. directly opposes it

D. cross-magnetises it

5979. A synchronous motor has better power factor as compared to that of an equivalent induction motor. This is mainly because?
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A. mechanical load on the rotor remains constant

B. synchronous motor has large airgap

C. stator supply is not required to produce magnetic field

D. synchronous motor has no slip

5980. The efficiency of a properly designed synchronous motor will usually fall in range___________?
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A. 99 to 99.5%

B. 75 to 80%

C. 85 to 95%

D. 60 to 70%