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
7001. impose limitation on design____________?
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A. Power factor

B. Efficiency

C. All above

D. Saturation

E. Temperature rise

7002. The action of electromagnetic machines can be related to which of the following basic principles __________?
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A. Induction

B. Interaction

C. Alignment

D. All of the above
7003. Direct water cooling of rotor winding presents_____________?
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A. none of the above

B. lesser mechanical difficulties

C. no mechanical difficulties

D. greater mechanical difficulties
7004. When the two coil sides forming a coil are spaced exactly one pole pitch apart they are said to be of_____________?
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A. full pitch

B. none of the above

C. either of the above

D. short pitch

7005. The length cf air gap to be provided in __________ is primarily determined by power factor consideration?
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A. d.c. shunt motor

B. induction motor

C. d.c. series motor .

D. synchronous motor

7006. Hot rolled sheets have ___________ value of permeability?
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A. low

B. zero

C. none of the above

D. high

7007. The insulation between windings and grounded core and the insulation between the windings of the same phase is called__________________?
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A. minor insulation

B. either of the above

C. none of the above

D. major insulation
7008. In _________ machines, the size of the shaft is decided by the critical speed which depends on the deflection of the shaft?
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A. medium

B. any of the above.

C. small

D. large
7009. With direct water cooling it is possible to have ratings of about_____________?
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A. 300 MW

B. 400 MW

C. 600 MW

D. 200 MW

7010. The input impedance of a JFET is _____________that of an ordinary transistor?
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A. less than

B. more than

C. none of the above

D. equal to

7011. __________is extensively used for those portions of magnetic circuit which carry steady flux and need superior mechanical properties ?
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A. Grey cast-iron

B. Stainless steel

C. High carbon steel

D. Cast steel
7012. A practical formula for determining the thickness of insulation between low voltage and high voltage windings is__________________?
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A. 1 + 0.2 kVmm

B. 5 + 0.9 kV mm

C. 2 + 0.5 kVmm

D. 4 + 0.7 kV mm

7013. Which of the following in an application of D.C. motors?
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A. Battery driven vehicles

B. All of the above

C. Traction

D. Automatic control

E. Drives for process industry

7014. D.C. windings are____________?
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A. none of the above

B. never 2-layer type

C. always 2-layer type

D. sometimes 2-layer type

7015. By which of the following methods the temperature rise of windings and other parts may be determined ?
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A. Embedded temperature detector method

B. Resistance method

C. Thermometer method

D. Any of the above
7016. Commercial available medium size machines have a speed range of __________ ?
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A. 600 to 1000 r.p.m

B. 2000 to 2500 r.p.m

C. 1000 to 1500 r.p.m

D. 200 to 400 r.p.m

7017. The surge phenomenon is particularly important in case of_______________?
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A. high voltage transformers

B. medium voltage transformers

C. any of the above

D. low voltage transformers

7018. The voltage control in electric supply networks in required on account of which of the following reasons ?
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A. All of the above

B. Control of active and reactive power

C. Adjustment of voltage at consumers premises within statutory limits

D. Adjustment of short period daily and seasonal voltage variations in accordance with variations of load

7019. The laminations of the armature of a D.C. machine are usually ___________ thick?
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A. 0.2 to 0.3 mm

B. 0.3 to 0.4 mm

C. 0.1 to 0.2 mm

D. 0.4 to 0.5 mm
7020. Tractive magnets are operated from____________?
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A. either a.c. or d.c. supply

B. d.c. supply

C. none of the above</strong>

D. a.c. supply

7021. Machines cooled by direct cooling method may be called_____________?
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A. any of the above

B. supercharged

C. inner cooled

D. conductor cooled

7022. In a D.C. machine the current per brush arm should not be more than_____________?
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A. 300 A

B. 200 A

C. 400 A

D. 100 A

7023. The cold rolled grain oriented steel has ___________ permeability in the direction of the grain orientation?
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A. nil

B. maximum

C. minimum

D. none of the above

7024. Electrical machines having a power output up to about 750 W may be called__________machines?
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A. any of the above

B. large size

C. medium size

D. small size
7025. The value of exciting or magnetizing current depends upon which of the following factors ?
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A. The number of turns in the exciting winding

B. All of the above

C. The way in which the winding is distributed

D. Total m.m.f. required

7026. Yokes with rectangular cross-section are used for_______________?
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A. any of the above

B. large capacity transformers

C. medium capacity transformers

D. small capacity transformers
7027. In D.C. machines, ir order to prevent excessive distortion of field form by the armature reaction, the field mmf must be made____________?
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A. less in comparison with the armature mmf

B. large in comparison with the armature mmf

C. none of the above

D. equal to that of armature mmf

7028. Which of the following methods is most accurate ?
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A. Method of average losses

B. Equivalent power method

C. Equivalent torque method

D. Equivalent current method
7029. Electrical machines having power outputs ranging from a few kW up to approximately 250 kW may be classified as_____________?
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A. any of the above

B. medium size machines

C. large size machines

D. small size machines

7030. __________ has a low relative permeability and is used principally in field frames when cost is of primary importance and extra weight is not objectionable?
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A. Soft steel

B. Aluminium

C. Cast iron

D. Cast steel

7031. Disc windings are primarily used in_____________-?
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A. medium capacity transformers

B. short capacity transformers

C. high capacity transformers

D. any of the above

7032. Transformers with a capacity of up to __________ have a cooling radiator system with natural cooling?
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A. 5 MVA

B. 2 MVA

C. 7.5 MVA

D. 10 MVA
7033. In D.C. machines the usual limit of slot pitch is________________?
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A. between 5 to 10 mm

B. between 15 to 20 mm

C. between 10 to 15 mm

D. between 25 to 35 mm
7034. On which of the following variables heat convected depends ?
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A. Gravitational constant

B. Thermal resistivity, density, specific heat

C. All of the above

D. Temperature difference between heated surface and coolant

E. Power density

7035. The noise produced by a ___________ cooled machine is less as the rotor moves in a medium of smaller density?
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A. hydrogen

B. air

C. none of the above

D. either A. or B.

7036. The flash point of transformer oil should be higher than_______________?
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A. 104C

B. 60C

C. 80C

D. 40C

7037. Materials exhibiting zero value of resistivity are known as ____________ ?
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A. conductors

B. superconductors

C. insulators

D. semiconductors

7038. The distance between the starts of two consecutive coils measured in terms of coil sides is called_____________?
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A. winding pitch

B. back pitch

C. commutator pitch

D. front pitch

7039. For 275 kV transformers, using cold rolled grain oriented steel, which of the following values of flux density may be used?
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A. 1.6 Wb/m2

B. None of the above

C. 1.0 Wb/m2

D. 1.1 Wb/m2

E. 1.3 Wb/m2

7040. The slot leakage can be calculated by making which of the following assumptions ?
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A. All of the above

B. The leakage path is straight across the slot and around the iron at the bottom

C. The permanence of air paths is only considered. The reluctance of iron paths is assumed as zero

D. The current in the slot conductors is uniformly distributed over their cross-section

7041. The heat dissipating capability of transformers of ratings higher than 30 kVA in increased by providing which of the following ?
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A. Corrugations

B. Fins

C. All of the above

D. Tubes

E. Radiator tanks

7042. Which of the following methods is used for air cooling of turbo-alternators ?
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A. All of the above

B. One sided axial ventilation

C. Two sided axial ventilation

D. Multiple inlet system

7043. Which of the following problem arises in D.C. motors which are fed from thyristor bridge circuits ?
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A. Increased I R losses

B. Increased core losses

C. Poor commutation

D. All of the above

E. Change in motor parameters

7044. The heat dissipated by from a surface depends upon its temperature and its characteristics like colour, roughness etc?
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A. convection

B. conduction

C. radiation

D. any of the above

7045. In D.C. machines the number of slots per pole usually lies___________?
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A. between 2 to 4

B. between 9 to 16

C. between 6 to 8

D. between 20 to 30

7046. With conventional hydrogen cooling it is possible to increase the rating of a single unit to___________?
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A. 200 MW

B. 50 MW

C. 100 MW

D. none of the above

7047. Which of the following methods does not take into account the maximum temperature rise under variable load conditions ?
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A. Equivalent power method

B. Method of average losses

C. Equivalent torque method

D. Equivalent current method

7048. Helical windings are used in________________?
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A. shell type transformers

B. none of the above

C. power transformers

D. distribution transformers

7049. The high voltage winding is usually which of the following type ?
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A. Continuous disc type winding with rectangular conductors

B. Cross-over winding with either circular or small rectangular conductors

C. Cylindrical winding with circular conductors

D. All of the above types
7050. The weight of copper of both armature and field windings decreases with __________ in number of poles?
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A. none of the above

B. decrease

C. either of the above

D. increase