A. 2 : 3
B. 3 : 1
C. 3 : 2
D. 1 : 3
D.C. Generators
In case of a 4-pole D.C. generator provided with a two layer lap winding with sixteen coils, the pole pitch will be__________________?
A. 4
B. 8
C. 16
D. 32
The purpose of providing dummy coils in a generator is__________________?
A. to reduce eddy current losses
B. to enhance flux density
C. to amplify voltage
D. to provide mechanical balance for the rotor
Iron losses in a D.C. machine are independent of variations in_____________?
A. speed
B. load
C. voltage
D. speed and voltage
Which of the following statement about D.C. generators is false ?
A. Compensating winding in a D.C. machine helps in commutation
B. In a D. C. generator interpoles winding is connected in series with the armature winding
C. Back pitch and front pitch are both odd and approximately equal to the pole pitch
D. Equilizing bus bars are used with parallel running of D.C. shunt gen¬erators
In D.C. generators, the cause of rapid brush wear may be___________?
A. severe sparking
B. rough commutator surface
C. imperfect contact
D. any of the above
The resistance of armature winding depends on
A. length of conductor
B. cross-sectional area of the conductor
C. number of conductors
D. all of the above
Satisfactory commutation of D.C. machines requires______________?
A. brushes should be of proper grade and size
B. brushes should smoothly run in the holders
C. smooth, concentric commutator properly undercut
D. all of the above
In case of D.C. machine winding, number of commutator segments is equal to______________?
A. number of armature coils
B. number of armature coil sides
C. number of armature conductors
D. number of armature turns
A D.C. welding generator has____________?
A. lap winding
B. wave moving
C. duplex winding
D. any of the above
