DC MACHINES 1

DC MACHINES MCQ 1

1.  In a d.c. motor the iron losses occur in
a) the yoke
b) the armature
c) the field.
d) None of these.
ans. a

2. The dummy coil in d.c. machines used to
a) eliminate reactance voltage.
b) eliminate armature reaction.
c) bring about mechanical balance of armature.
d) eliminate harmonics developed in the machine.
ans. c

3. A simple method of increasing the voltage of an d.c. generator is
a) to decrease the air gap flux density
b) to increase the speed of rotation.
c) to decrease the speed of rotation.
d) to increase the length of the armature.
ans. b

4. The function of starter in a d.c. machine is
a) to avoid the excessive current at starting
b) to control the speed.
c) to avoid armature reaction.
d) to increase the length of the armature.
ans. b

5. An external resistance is added in the series with the field of a d.c. shunt motor. When the motor runs, the effect of resistance is
a) to reduce the speed of the motor
b) to increase the speed of the motor.
c) to reduce the armature current drawn by the motor
d) to reduce the losses.
ans. b

6. D.C. shunt generator has
a) slightly drooping characteristics.
b) appreciably rising characteristics.
c) constant voltage characteristics.
d) appreciably falling characteristics.
ans. a

7. which one of the following is used for charging batteries?
a) compound generator.
b) shunt generator.
c) series generator.
d) tacho generator.
ans. b

8. The speed of a d.c. motor is
a) directly proportional to back emf and inversely proportional to flux.
b) inversely proportional to back emf and directly proportional to flux.
c) directly proportional to emf as well as flux.
d) inversely proportional to emf as well as flux.
ans. a

9. In any d.c. generator the emf generated in the armature is maximum when
a) rate of change of flux linked is minimum.
b) rate of change of flux linked is maximum.
c) flux linked with conductor is maximum.
d) flux linked with conductor is minimum.
ans. b

10. The highest speed attained by a d.c. shunt motor is
a) equal to infinity at rated flux.
b) higher than no load speed at rated flux.
c) equal to no load speed at rated flux.
d) lower than no load speed at rated flux.
ans. c

 Click To Read More DC Machine MCQ :  DC Machine