100 TOP D.C Motors Multiple choice Questions and Answers pdf

81.    If the terminals of armature of D.C. motor are interchanged, this action will offer following kind of braking
(o)     regenerative 
(b)     plugging
(c)    dynamic braking
(d)    none of the above
(e)    any of the above
Ans: b

82.    Which of the following motors one will choose to drive the rotary compressor ?
(a)    D.C. shunt motor
(b)    D.C. series motor
(c)    Universal motor
(d)    Synchronous motor
Ans: d

83.    If the speed of a D.C. shunt motor is increased, the back e.m.f. of the motor will
(a) increase
(b) decrease
(c) remain same 
(d) become zero
Ans: a

84.    Why are the D.C. motors preferred for traction applications ?
(a)    Torque and speed are inversely proportional to armature current
(b)    Torque is proportional to armature current
(c)    Torque is proportional to square root of armature current
(d)    The speed is inversely proportional to the torque and the torque is proportional to square of armature current
Ans: d

85.    Which of the following motors is usually used in house-hold refrigerators ?
(a)     D.C. shunt motor
(b)     D.C. series motor
(c)    Single phase induction motor (split phase start or induction run motor)
(d)    Reluctance motor
(e)    Synchronous motor
Ans: c

86.    Which of the following motors is most suitable for signalling devices and many kinds of timers ?
(a)    D.C. shunt motor
(b)    D.C. series motor
(c)    Induction motor
(d)    Reluctance motor
Ans: d

87.    Which motor should not be started on no-load ?
(a) Series motor 
(b) Shunt motor
(c) Cumulatively compounded motor
(d) Differentially compounded motor.
Ans: a

88.    Ward-Leonard control is basically a
(a) voltage control method
(b) field divertor method
(c) field control method
(d) armature resistance control method
Ans: a

89.    For constant torque drive which speed control method is preferred ?
(a) Field control
(b) Armature voltage control
(c) Shunt armature control
(d) Mechanical loading system
Ans: b

90.    In Ward-Leonard control  the lower limit of speed is imposed by
(a)    residual magnetism of the generator
(b)    core losses of motor
(c)    mechanical losses of motor and gen¬erator together
(d)    all of the above
Ans: a

Read More Questions:
D.C Motors MCQs Part1
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