A. identified by the scarring of the commutator segment to which open circuited coil is connected
B. indicated by a spark completely around the commutator
C. both A. and (b)
D. none of the above
Related Mcqs:
- Armature coil is short circuited by brushes when it lies_____________?
A. along neutral axis
B. along field axis
C. in any of the above positions
D. in none of the above positions - 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 - Two generators A and B have 6-poles each. Generator A has wave wound armature while generator B has lap wound armature. The ratio of the induced e.m.f. is generator A and B will be_______________?
A. 2 : 3
B. 3 : 1
C. 3 : 2
D. 1 : 3 - Armature reaction of an unsaturated D.C. machine is_____________?
A. crossmagnetising
B. demagnetising
C. magnetising
D. none of 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 - Equilizer rings are required in case armature is_______________?
A. wave wound
B. lap wound
C. delta wound
D. duplex wound - The demagnetising component of armature reaction in a D.C. generator___________?
A. reduces generator e.m.f.
B. increases armature speed
C. reduces interpoles flux density
D. results in sparking trouble - The armature core of a D.C. generator is usually made of__________________?
A. silicon steel
B. copper
C. non-ferrous material
D. cast-iron - A sinusoidal voltage of 5 Hz is applied to the field of a shunt generator. The armature voltage wave will_____________?
A. will be zero
B. will be of 5 Hz
C. will be of 5 xiVHz
D. will be of v Hz 5 - As a result of armature reaction, the reduction in the total mutual air gap flux in a D.C. generator is approximately______________?
A. 40 percent
B. 25 percent
C. 10 percent
D. 5 percent
