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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-14


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91. The function of a field regulator for compound motors is to

A) control the flux
B) limit the armature current
C) demagnetize the magnetic field partially
D) increases the armature resistance.

Ans : (A)

92. If the speed of a shunt motor is to be controlled between zero and normal running speed N, the most practical way to achieve this would be to insert a resistance of suitable value in

A) series with the armature
B) parallel with the armature
C) series with the field
D) parallel with the field.

Ans : (A)

93. The function of the started for a dc motor is

A) to reduce armature resistance
B) to increase field resistance
C) to limit the starting voltage
D) to limit the starting current.

Ans : (D)

94. Which losses can be determined by performing the retardation test ?

A) Eddy current losses
B) Friction losses
C) Stray losses
D) Copper losses.

Ans : (C)

95. Which test can be used for estimating no-load losses in a large dc shunt motor ?

A) Swinburne test
B) Hopkinson test
C) Leonard test
D) Block rotor test.

Ans : (A)

96. In case a compound motor is started with an open series field

A) the fuse will blow off
B) the motor will not start
C) the motor will start with jerk
D) the motor will run with vibrations and noise.

Ans : (B)

97. The starting resistor is connected in

A) series with the armature
B) parallel across the armature
C) parallel across the field winding
D) series with the field winding.

Ans : (A)

98. The generated emf and the current are in the opposite direction in the case of

A) dc generators
B) dc motors
C) both dc motors as well as dc generators
D) neither dc motors nor dc generators.

Ans : (B)

99. The electromagnetic torque and speed are in the same direction in the case of

A) dc motors
B) dc generators
C) both dc generators as well as dc motors
D) none of the above.

Ans : (A)

100. If a kΩ resistor is connected to the terminals of this generator, what is the resulting induced counter-torque on the shaft of the machine?

A) 111 N-m
B) 248 N-m
C) 156 N-m
D) 396 N-m.

Ans : (D)


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