Top 350+ Solved Electrical Machine 1 MCQ Questions Answer
Q. For a D.C. shunt motor if the excitation is changed
a. torque will remain constant
b. torque will change but power will remain constant
c. torque and power both will change
d. torque, power and speed, all will change
Q. Which motor has the poorest speed control?
a. Differentially compounded motor
b. Cumulatively compoundedmotor
c. Shunt motor
d. Series motor
Q. The plugging gives the
a. zero torque braking
b. smallest torque braking
c. highest torque braking
d. none of the above
Q. The armature voltage control of D.C. motor provides
a. constant voltage drive
b. constant current drive
c. constant torque drive
d. none of the above
Q. If a D.C. motor designed for 40°C ambient temperature is to be used for 50°C ambient temperature, then the motor
a. of lower H.P. should be selected
b. of higher H.P. should be selected
c. can be used for 50°C ambient temperature also
d. is to be derated by a factor recom-mended by manufacturer and select the next higher H.P. motor
Q. If the terminals of armature of D.C. motor are interchanged, this action will offer following kind of braking
a. regenerative
b. plugging
c. dynamic braking
d. none of the above
Q. 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
Q. 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
Q. 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
Q. 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
Q. Which of the following motors is most suitable for signalling devices and many kinds oftimers ?
a. D.C. shunt motor
b. D.C. series motor
c. Induction motor
d. Reluctance motor
Q. Which motor should not be started on no-load ?
a. Series motor
b. Shunt motor
c. Cumulatively compounded motor
d. Differentially compounded motor.
Q. Ward-Leonard control is basically a
a. voltage control method
b. field divertor method
c. field control method
d. armature resistance control method
Q. 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
Q. 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