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SymbolsTransformerRelayPower-SystemBasic-electricalACSR-ConductorCircuit-BreakerInterview-questions-of-Basic-ElectricityInterview-questions-of-transformerInsulatorCurrent-TransformerMCQMCQ-powersystemThermal-power-stationInterview-questions-of-Power-SystemPower-ElectronicsInterview-questions-of-Underground-CableInterview-questions-of-IlluminationIlluminationMCQ-of-ElectronicsMCQ-of-Basic-ElectricalMCQ-of-Transformers MCQ-of-D.C-motor MCQ-of-D.C-generatorsMCQ-Control-SystemMCQ-Measurementsmcq-of-Generation-power-systemMCQ-of-Induction-MotorMCQ-of-Transmission-DistributionMCQ-of-Electrical-MachinesMCQ-of-Alternator-and-Synchronous-MotorsMCQ-Electric-PowerMCQ-Illumination

MCQ of D.C motor page-15


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101. At no-load, the ratio of energy loss due to dynamic braking and counter current braking of a separately excited DC motor is

A) 1 : 3
B) 1 : 2
C) 3 : 1
D) 2 : 1.

Ans : (A)

102. The direction of rotation of a compound dc motor can be effectively reversed by interchanging

A) line leads
B) armature connections
C) series field connections
D) shunt field connections.

Ans : (B)

103. A dc motor can be easily identified by

A) winding
B) commutator
C) size of conductor
D) yoke.

Ans : (B)

104. In a compound dc motor, the shunt field winding as compared to series field winding will have

A) less turns and a smaller cross-section of wire
B) more turns and a large cross-section of wire
C) less turns and a large cross-section of wire
D) more turns and a smaller cross-section of wire.

Ans : (D)

105. The function of a brush and commutator arrangement is a DC motor is to

A) Produce unidirectional torque
B) Produce unidirectional current in the armature
C) Help in changing the direction of rotation of the armature
D) Reduce sparking.

Ans : (A)

106. The direction of rotation of a cumulatively compound dc motor can be reversed by reversing the connection to the

A) shunt field
B) series field
C) armature
D) any of the above.

Ans : (C)

107. In which of the following test only one motor is required?

A) Hopkinson’s test
B) Brake test
C) Field’s test
D) All of the above.

Ans : (B)

108. In fields test for series motors, one motor drives the other machine as

A) separately excited generator
B) series generator
C) differentially compound generator
D) cumulatively compound generator.

Ans : (A)

109. In fields test fields of two series motors are connected in series so as to

A) mechanical losses of both machines equal
B) total losses of both machines equal
C) copper losses of both machines equal
D) make iron losses of both machines equal.

Ans : (D)

110. Which of the following loss of motor decreases with increase in load?

A) Core loss
B) Friction and windage loss
C) Brush contact loss
D) None of the above.

Ans : (D)


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