In D.C. generators, the brushes on commutator remain in contact with conductors which_________________?
(A) lie under south pole
(B) lie under north pole
(C) lie under interpolar region
(D) are farthest from the poles
The insulating material used between the commutator segments is normally_____________?
(A) graphite
(B) paper
(C) mica
(D) insulating varnish
The material for commutator brushes is generally_______________?
(A) mica
(B) copper
(C) cast iron
(D) carbon
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
To achieve sparkless commutation brushes of a D.C. generator are rockedm ahead so as to bring them?
(A) just ahead of magnetic neutral axis
(B) in magnetic neutral axis
(C) just behind the magnetic neutral axis
(D) none
A D.C. welding generator has____________?
(A) lap winding
(B) wave moving
(C) duplex winding
(D) any of the above
In a D.C. generator the critical resistance refers to the resistance of_____________?
(A) brushes
(B) field
(C) armature
(D) load
The e.m.f. induced in the armature of a shunt generator is 600 V. The armature resistance is 0.1 ohm. If the armature current is 200 A, the terminal voltage will be_____________?
(A) 640 V
(B) 620 V
(C) 600 V
(D) 580 V
In the case of lap winding resultant pitch is____________?
(A) multiplication of front and back pitches
(B) division of front pitch by back pitch
(C) sum of front and back pitches
(D) difference of front and back pitches
The function of pole shoes in the case of D.C. machine is______________?
(A) to reduce the reluctance of the mag¬netic path
(B) to spread out the flux to achieve uniform flux density
(C) to support the field coil
(D) to discharge all the above functions