Explore topic-wise MCQs in Electrical Engineering Questions.

This section includes 102 Mcqs, each offering curated multiple-choice questions to sharpen your Electrical Engineering Questions knowledge and support exam preparation. Choose a topic below to get started.

1.

Dummy coil should not be used in_________________?
A. small machines
B. large machines
C. either A. or B.
D. none of the above
Answer» C. either A. or B.
Discussion
2.

Which of the following methods is most accurate ?
A. Equivalent current method
B. Equivalent power method
C. Equivalent torque method
D. Method of average losses
Answer» B. Equivalent power method
Discussion
3.

electromagnets generally function as holding magnets ?
A. Tractive
B. Portative
C. Either of the above
D. None of the above
Answer» C. Either of the above
Discussion
4.

cooling is the process of dissipating the armature and field winding losses to a cooling medium circulating within the winding insulation wall______________?
A. Direct
B. Indirect
C. Conventional
D. Any of the above
Answer» B. Indirect
Discussion
5.

In D.C. machines the width of the duct is usually_____________?
A. 4 mm
B. 6 mm
C. 8 mm
D. 10 mm
Answer» E.
Discussion
6.

For large power transformers, self oil cooled type or air blast type which of the following values of current density may be used?
A. 1.0 to 1.2 A/mm2
B. 1.5 to 2.0 A/mm2
C. 2.2 to 3.2 A/mm2
D. 3.2 to 4.2 A/mm2
Answer» D. 3.2 to 4.2 A/mm2
Discussion
7.

The weight of copper of both armature and field windings decreases with __________ in number of poles?
A. increase
B. decrease
C. either of the above
D. none of the above
Answer» B. decrease
Discussion
8.

The thermal conductivity of hydrogen is _____________ times that of air?
A. 2
B. 3
C. 5
D. 7
Answer» E.
Discussion
9.

A practical formula for determining the thickness of insulation between low voltage and high voltage windings is__________________?
A. 1 + 0.2 kVmm
B. 2 + 0.5 kVmm
C. 4 + 0.7 kV mm
D. 5 + 0.9 kV mm
Answer» E.
Discussion
10.

Which of the following materials is used in the manufacture of resistance grids to be used in the starters of large motors ?
A. Copper
B. Aluminium
C. Steel
D. Cast-iron
Answer» E.
Discussion
11.

Hydrogen has a heat transfer co-efficient __________ times that of air?
A. 1.5
B. 2.5
C. 3.5
D. 4.5
Answer» B. 2.5
Discussion
12.

In _________ machines, the size of the shaft is decided by the critical speed which depends on the deflection of the shaft?
A. small
B. medium
C. large
D. any of the above
Answer» D. any of the above
Discussion
13.

On which of the following variables heat convected depends ?
A. Power density
B. Temperature difference between heated surface and coolant
C. Thermal resistivity, density, specific heat
D. Gravitational constant
E. All of the above
Answer» F.
Discussion
14.

The efficiency of a machine should be as ____________ as possible to reduce the operating cost?
A. high
B. low
C. either of the above
D. none of the above
Answer» B. low
Discussion
15.

Multiple inlet system of air cooling of turbo-alternators can be used for machines of rating upto_______________?
A. 10 MW
B. 30 MW
C. 60 MW
D. 150 MW
Answer» D. 150 MW
Discussion
16.

The heated parts of an electrical machine dissipate heat into their surroundings by which of the following modes of heat dissipation ?
A. Conduction
B. Convection
C. Radiation
D. All of the above
Answer» E.
Discussion
17.

Which of the following is an advantage of hydrogen cooling ?
A. Increase in efficiency
B. Increase in ratings
C. Increase in life
D. Smaller size of coolers
E. All of the above
Answer» F.
Discussion
18.

The mcrease in heat dissipation by air blasts is due to increase in______________?
A. conduction
B. convection
C. radiation
D. any ofthe above
Answer» C. radiation
Discussion
19.

The noise produced by a ___________ cooled machine is less as the rotor moves in a medium of smaller density?
A. air
B. hydrogen
C. either A. or B.
D. none of the above
Answer» C. either A. or B.
Discussion
20.

With conventional hydrogen cooling it is possible to increase the rating of a single unit to___________?
A. 50 MW
B. 100 MW
C. 200 MW
D. none of the above
Answer» D. none of the above
Discussion
21.

In direct cooled system using hydrogen both stator and rotor conductors are made____________?
A. solid
B. hollow
C. perforated
D. any ofthe above
Answer» C. perforated
Discussion
22.

The density of hydrogen is __________ times the density of air?
A. 0.07
B. 1.5
C. 2.5
D. 3.5
Answer» B. 1.5
Discussion
23.

Machines cooled by direct cooling method may be called_____________?
A. “supercharged”
B. “inner cooled”
C. “conductor cooled”
D. any of the above
Answer» E.
Discussion
24.

With direct water cooling it is possible to have ratings of about_____________?
A. 200 MW
B. 300 MW
C. 400 MW
D. 600 MW
Answer» E.
Discussion
25.

Direct water cooling of rotor winding presents_____________?
A. no mechanical difficulties
B. lesser mechanical difficulties
C. greater mechanical difficulties
D. none of the above
Answer» D. none of the above
Discussion
26.

The resistivity of water should not be less than_____________?
A. 10 Q m
B. 100 Q m
C. 1000 Q m
D. 2000 Q m
Answer» E.
Discussion
27.

In self cooled motors the cooling time constant is about ___________ than the heating time constant because cooling conditions are worse at standstill?
A. 2 to 3 times greater
B. 3 to 4 times greater
C. 4 to 5 times greater
D. none of the above
Answer» B. 3 to 4 times greater
Discussion
28.

The change in flux linkages can be caused in which of the following ways ?
A. The flux is constant with respect to time and is stationary and the coil moves through it
B. The coil is stationary with respect to flux and the flux varies in magnitude with respect to time
C. Both the changes mentioned above occur together, i.e., the coil moves through a time varying field
D. All of the above
Answer» E.
Discussion
29.

The action of electromagnetic machines can be related to which of the following basic principles __________?
A. Induction
B. Interaction
C. Alignment
D. All of the above
Answer» E.
Discussion
30.

The time taken by the machine to attain 0.632 of its final steady temperature rise is called_____________?
A. heating time constant
B. cooling time constant
C. either A. or B.
D. none of the above
Answer» B. cooling time constant
Discussion
31.

Materials exhibiting zero value of resistivity are known as ____________ ?
A. conductors
B. semiconductors
C. insulators
D. superconductors
Answer» E.
Discussion
32.

Commercial available medium size machines have a speed range of __________ ?
A. 200 to 400 r.p.m
B. 600 to 1000 r.p.m
C. 1000 to 1500 r.p.m
D. 2000 to 2500 r.p.m
Answer» E.
Discussion
33.

__________is extensively used for those portions of magnetic circuit which carry steady flux and need superior mechanical properties ?
A. Grey cast-iron
B. Cast steel
C. High carbon steel
D. Stainless steel
Answer» C. High carbon steel
Discussion
34.

__________ has a low relative permeability and is used principally in field frames when cost is of primary importance and extra weight is not objectionable?
A. Cast steel
B. Aluminium
C. Soft steel
D. Cast iron
Answer» E.
Discussion
35.

_______________is universally used for windings of electrical machines because it is easily workable without any possibility of fracture?
A. Silver
B. Steel
C. Aluminium
D. Copper
Answer» E.
Discussion
36.

Hot rolled sheets have ___________ value of permeability?
A. zero
B. low
C. high
D. none of the above
Answer» C. high
Discussion
37.

Aluminium when adopted as a conductor material in __________ transformers, decreases the overall cost of the transformer?
A. small size
B. medium size
C. large size
D. any of the above size
Answer» B. medium size
Discussion
38.

The heat dissipated by from a surface depends upon its temperature and its characteristics like colour, roughness etc?
A. conduction
B. convection
C. radiation
D. any of the above
Answer» D. any of the above
Discussion
39.

The design of mechanical parts is particularly important in case of __________ speed machines?
A. low
B. medium
C. high
D. any of the above
Answer» D. any of the above
Discussion
40.

Which of the following methods does not take into account the maximum temperature rise under variable load conditions ?
A. Equivalent power method
B. Equivalent current method
C. Method of average losses
D. Equivalent torque method
Answer» D. Equivalent torque method
Discussion
41.

The length cf air gap to be provided in __________ is primarily determined by power factor consideration?
A. d.c. series motor
B. d.c. shunt motor
C. induction motor
D. synchronous motor
Answer» D. synchronous motor
Discussion
42.

Which of the following is the major consideration to evolve a good design ?
A. Cost
B. Durability
C. Compliance with performance criteria as laid down in specifications
D. All of the above
Answer» E.
Discussion
43.

In induction motors, the length of air gap in kept as small as mechanically possible is order to have____________?
A. low power factor
B. high power factor
C. high over load capacity
D. any of the above
Answer» C. high over load capacity
Discussion
44.

impose limitation on design____________?
A. Saturation
B. Temperature rise
C. Efficiency
D. Power factor
E. All above
Answer» F.
Discussion
45.

If an insulating material is operated beyond the maximum allowable temperature, its life is_____________?
A. drastically increased
B. drastically reduced
C. unaffected
D. none of the above
Answer» C. unaffected
Discussion
46.

Which of the following brushes can be used for high values of current density ?
A. Metal graphite brushes
B. Hard carbon brushes
C. Electro-graphitic brushes
D. Natural graphite brushes
Answer» B. Hard carbon brushes
Discussion
47.

For 275 kV transformers, using cold rolled grain oriented steel, which of the following values of flux density may be used?
A. 1.0 Wb/m2
B. 1.1 Wb/m2
C. 1.3 Wb/m2
D. 1.6 Wb/m2
E. None of the above
Answer» E. None of the above
Discussion
48.

Which of the following is the basic consideration in the design of insulation ?
A. Electrical considerations
B. Mechanical considerations
C. Thermal considerations
D. All of the above
Answer» E.
Discussion
49.

A current density of __________ is ilsed for large power transformers with forced circulation of oil or with water cooling coils?
A. 1.5 to 2.5 A/mm2
B. 3.5 to 4.5 A/mm2
C. 4.0 to 5.0 A/mm2
D. 5.4 to 6.2 A/mm2
Answer» E.
Discussion
50.

Transformers with a capacity of up to __________ have a cooling radiator system with natural cooling?
A. 2 MVA
B. 5 MVA
C. 7.5 MVA
D. 10 MVA
Answer» E.
Discussion