electrical engineering MCQs – Page 300

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 Review each marked answer and report any item that may be outdated or unclear.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 generation 2. analog electronics 3. solid state switching circuits 4. parallel circuits 5. switchgear and protection 6. op amp circuits 7. transistor audio power amplifiers 8. electrostatics 9. heating and welding 10. multi stage transistor amplifiers 11. passive filters 12. network theorems 13. regulated d c power supply 14. a c fundamentals circuits and circuit theory 15. electromagnetic induction 16. power electronics 17. magnetism and electromagnetism 18. transformers 19. modulation and demodulation 20. d c generators 21. semiconductor theory 22. single phase induction motors 23. semiconductor diode 24. hybrid parameters 25. digital electronics 26. oscillators 27. earthing or grounding 28. single stage transistor amplifiers 29. d c motors 30. transistor biasing 31. amplifiers with negative feedback 32. basic electrical 33. electronic instruments 34. synchronous motors 35. field effect transistors fet 36. magnetic circuit 37. control systems 38. industrial drives 39. power generation 40. series parallel circuits 41. transistor tuned amplifiers 42. electrical engineering materials 43. rectifiers and converters 44. integrated circuits 45. scr silicon controlled rectifiers 46. cables 47. polyphase induction motors 48. measurement and instrumentation 49. transistors 50. electrical machine design 51. electrolysis and storage of batteries 52. electric traction 53. transmission and distribution

5981. The working of a synchronous motor is similar to_____________?
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A. turbine

B. transmission of mechanical power by shaft

C. distribution transformer

D. none of the above

E. gear train arrangement

5982. The armature current of the synchronous motor has higher values for_____________?
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A. high excitation only

B. low excitation only

C. both A. and (b)

D. none of the above

5983. The back e.m.f. in the stator of a synchronous motor depends on____________?
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A. flux density

B. none of the above

C. rotor speed

D. number of poles

E. rotor excitation

5984. A synchronous motor can be started by________?
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A. providing damper winding

B. D.C. compound motor

C. pony motor

D. any of the above

5985. In a 3-phase synchronous motor, the negative phase sequence exists when the motor is_______________?
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A. under-loaded

B. supplied with unbalanced voltage

C. over-loaded

D. none of the above

5986. Synchronous motor always runs at______________?
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A. less than synchronous speed

B. none of the above

C. the synchronous speed

D. more than synchronous speed

5987. Which of the following methods is used to start a synchronous motor?
0

A. Damper winding

B. Star-delta starter

C. Resistance starter in the armature circuit

D. Damper winding in conjunction with star-delta starter

5988. An important advantage of a synchronous motor over wound round induction motor is that
0

A. none of the above

B. its speed may be controlled more easily

C. its speed is independent of supply frequency

D. its power factor may be varied at will

5989. The maximum value of torque that a synchronous motor can develop without losing its synchronism, is known as_____________?
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A. slip torque

B. pull-out torque

C. synchronising torque

D. breaking torque

5990. If in a synchronous motor, driving a given mechanical load and drawing current at a leading power factor from constant voltage supply its field excitation is increased, its power factor
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A. will become more

B. will remain unchanged

C. none of the above.

D. will become less

5991. The net armature voltage of a synchronous motor is equal to the_______________?
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A. arithmetic sum of Eb and V

B. arithmetic difference of Eb and V

C. vector sum of Eb and V

D. vector difference of Eh and V

5992. Power factor of a synchronous motor is unity when_____________?
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A. the armature current is minimum

B. none of the above

C. the armature current is maximum

D. the armature current is zero

5993. If the field circuit of an unloaded salientpole synchronous motor gets suddenly open-circuited, then
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A. the motor stops

B. it continues to run at the same speed

C. it runs at a very high speed

D. it runs at a slower speed

5994. In a 3-phase, 4-pole, 50 Hz synchronous motor, the frequency, pole number and load torque all are halved. The motor speed will be____________?
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A. 750 r.p.m.

B. 3000 r.p.m.

C. none of the above

D. 1500 r.p.m.

5995. A synchronous motor working at leading power factor can be used as____________?
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A. noise generator

B. voltage booster

C. mechanical synchronizer

D. phase advancer

5996. A synchronous motor develops maximum power when load angle is____________?
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A. 90

B. 45

C. 60

D. 120

5997. If excitation of a synchronous motor running with a constant load is decreased from its normal value, ignoring effects of armature reaction, it leads to____________?
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A. increase in both armature current and power factor angle

B. increase in back e.m.f. but decrease in armature current

C. increase in both armature current and power factor which is lagging

D. increase in torque angle but decrease in back e.m.f.

5998. Synchronsizing power of a synchronous machine is_____________?
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A. none of the above

B. direcly proportional to the synchronous reactance

C. equal to the synchronous reactance

D. inversely proportional to the synchronous reactance

5999. Stability of a synchronous machine:
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A. remains unaffected with increase in excitation

B. decreases with increase in its excitation

C. any of the above

D. increases with increase in its excitation

6000. In which of the following motors the stator and rotor magnetic field rotate at the same speed?
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A. Universal motor

B. Induction motor

C. Reluctance motor

D. Synchronous motor

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