MCQs on DC Machine

« Back         CONTENTS          Next »

 1. The armature winding of DC machine is placed on the rotor to
(a) reduce losses
(b) escalate commutation
(c) reduce armature reaction
(d) reduce weight           

 2. The yoke of a DC machine is generally made of
(a) carbon
(b) soft iron
(c) cast steel
(d) silicon steel 

3. Number of magnetic circuits in a four pole DC machine are
(a) one
(b) two
(c)  four
(d) eight     

4. The armature of DC machine is laminated in order to reduce
(a) copper losses
(b) hysteresis losses
(c) eddy current losses
(d) friction frictional losses 

5. In a DC Machine, the current flow in a armature circuit is
(a) AC
(b) pulsating DC
(c) pure DC
(d) none of the above  

6. The number of commutator segments in a DC machine is equal to
(a) number of poles
(b) number of conductors
(c) number of coils
(d) number of turns    

7. As the armature reaction effect increases, the main flux of DC machine is
(a) decreases
(b) increases
(c) remain same
(d) none of the above  

8. The space wave form of the air gap flux distribution of an DC machine will results change in
(a) current
(b) voltage
(c) torque
(d) none of the above 

9. In DC machines, slot wedges are generally made of
(a) silicon steel
(b) fibre
(c) impregnated paper
(d) cotton        

10. The number of brushes used in a lap wound DC machine is always equal to
(a) number of conductors
(b) number of poles
(c) number of coils
(d) number of pole pairs 

11. In which part of DC machine the eddy current loss is maximum
(a) yoke
(b) field pole
(c) air gap
(d) armature 

12. In order to reduce the size of DC generator, the magnetic material must have
(a) high permeability
(b) low permeability
(c) high resistance
(d) high reluctance 

13. In DC machine, the air gap flux distribution in space at no old is
(a) sinusoidal
(b) DC
(c) flat topped
(d) pulsuating       

14. In DC machine, the teeth in the armature are sometime skewed in order to reduce
(a) copper losses
(b) iron losses
(c) magnetic locking
(d) vibration   

15. In DC machines if the resistance of carbon brushes increases, the sparking at the brushes
(a) increases
(b) decreases
(c) remains same
(d) none of the above  

« BACK                                        NEXT »

Leave a Reply

Your email address will not be published. Required fields are marked *