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MCQ of D.C motor page-1MCQ of D.C motor page-2MCQ of D.C motor page-3MCQ of D.C motor page-4Multiple Choice Question (MCQ) of D.C. Machines page-1Multiple Choice Question (MCQ) of D.C. Machines page-2Multiple Choice Question (MCQ) of D.C. Machines page-3Multiple Choice Question (MCQ) of D.C. Machines page-4Multiple Choice Question (MCQ) of D.C. Machines page-5Multiple Choice Question (MCQ) of D.C. Machines page-6Multiple Choice Question (MCQ) of D.C. Machines page-7Multiple Choice Question (MCQ) of D.C. Machines page-8Multiple Choice Question (MCQ) of D.C. Machines page-9Multiple Choice Question (MCQ) of D.C. Machines page-10MCQ of D.C motor page-5MCQ of D.C motor page-6MCQ of D.C motor page-7MCQ of D.C motor page-8MCQ of D.C motor page-9MCQ of D.C motor page-10MCQ of D.C motor page-11MCQ of D.C motor page-12MCQ of D.C motor page-13MCQ of D.C motor page-14MCQ of D.C motor page-15MCQ of D.C motor page-16MCQ of D.C motor page-17MCQ of D.C motor page-18

Index

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-Power

MCQ of D.C motor page-13


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81. In series parallel control method when two dc series motors are connected in series, the speed of the combined set is

A) the same as the rated speed of the motor having lowest rpm
B) one fourth of the speed of the motors when connected in parallel
C) half the speed of motors when connected in parallel
D) the same as the speed of motors when connected in parallel.

Ans : (B)

82. Two series motors are mechanically coupled. One machine is run as motor and the other as generator. The iron and friction losses of the machines will be identical when

A) their rating and armature sizes are identical
B) their speeds are equal and back emfs are half the supply voltage
C) their speeds and excitations are identical
D) their speeds are identical.

Ans : (C)

83. In case the starting resistance of a series motor is short-circuited, the motor will

A) burn out
B) not start
C) run with excessive noise
D) run at very high rpm.

Ans : (D)

84. Two dc series motors are coupled. One motor is run as generator and the other as motor. The friction losses of the two machines will be equal when

A) both have same excitation
B) both have same speed
C) both have same back emf
D) both operate at same voltage.

Ans : (B)

85. Which of the following is likely to be the shunt field winding resistance for a 5 kW shunt motor

A) 0.1 ohm
B) 1 ohm
C) 200 ohms
D) 20000 ohms.

Ans : (C)

86. The brush voltage drop in dc motors is usually of the order of

A) 2 V
B) 20 V
C) 50 V
D) 100 V.

Ans : (A)

87. A dc shunt motor is started on no-load and runs at 400 rpm. The motors is made to run on no load for ten hours. The speed of the motors after ten hours will be

A) 400 rpm
B) more than 400 rpm
C) 380 rpm
D) less than 400 rpm.

Ans : (B)

88. In a permanent magnet dc motor which method of speed control cannot be used?

A) Armature voltage variation
B) Armature resistance control
C) Varying the field current
D) All of the above.

Ans : (C)

89. When the direction of power flow reverses, a cumulatively compounded motor become

A) A series generator
B) A shunt generator
C) A cumulatively compounded generator
D) A differentially compounded generator.

Ans : (D)

90. Frog-leg winding is

A) duplex wave winding on a single rotor
B) combined lap and wave winding on a single rotor
C) same as duplex winding
D) same as simplex winding.

Ans : (B)


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