Top 150+ Solved DC Motor MCQ Questions Answer
Q. Which of the following loss in a D.C. generator varies significantly with the loadcurrent ?
a. Field copper loss
b. Windage loss
c. Armature copper loss
d. None of the above
Q. Torque developed by a D.C. motor depends upon
a. magnetic field
b. active length of the conductor
c. current flow through the conductors
d. all above factors
Q. In a manual shunt motor starter
a. over load relay is connected in series and no volt relay in parallel with the load
b. over load relay is connected in paral¬lel and no volt relay in series with the load
c. over load relay and no volt relay are both connected in series with the load
d. over load relay and no volt relay are both connected in parallel with the load
Q. Which of the following steps is likely to result in reduction of hysteresis loss in a D.C.generator ?
a. Providing laminations in armature core
b. Providing laminations in stator
c. Using non-magnetic material for frame
d. Using material of low hysteresis co-efficient for armature core material
Q. Which of the following loss in a D.C. generator is dissipated in the form of heat?
a. Mechanical loss
b. Core loss
c. Copper loss
d. All of the above
Q. Which of the following losses are significantly reduced by laminating the core of aD.C. generator ?
a. Hysteresis losses
b. Eddy current losses
c. Copper losses
d. Windage losses
Q. The total losses in a well designed D.C. generator of 10 kW will be nearly
a. 100 W
b. 500 W
c. 1000 W
d. 1500 W
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 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. The condition for maximum efficiency for a D.C. generator is
a. eddy current losses = stray losses
b. hysteresis losses = eddy current losses
c. copper losses = 0
d. variable losses = constant losses
Q. D.C. generators are normally designed for maximum efficiency around
a. full-load
b. rated r.p.m.
c. rated voltage
d. all of the above
Q. In a D.C. generator, the iron losses mainly take place in
a. yoke
b. commutator
c. armature conductors
d. armature rotor
Q. D.C. generators are installed near the load centres to reduce
a. iron losses
b. line losses
c. sparking
d. corona losses