Top 150+ Solved DC Generators MCQ Questions Answer
Q. 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
Q. If a D.C. generator fails to build up the probable cause could not be
a. imperfect brush contact
b. field resistance less than the critical resistance
c. no residual magnetism in the generator
d. faulty shunt connections tending to reduce the residual magnetism
Q. Flashing the field of D.C. generator means
a. neutralising residual magnetism
b. creating residual magnetism by a D.C. source
c. making the magnetic losses of forces parallel
d. increasing flux density by adding extra turns of windings on poles
Q. In a D.C. generator the critical resistance refers to the resistance of
a. brushes
b. field
c. armature
d. load
Q. Following D.C. generator will be in a position to build up without anyresidual magnetism in the poles
a. series generator
b. shunt generator
c. compound generator
d. self-excited generator
Q. In a D.C. generator the number of mechanical degrees and electrical degreeswill be the same when
a. r.p.m. is more than 300
b. r.p.m. is less than 300
c. number of poles is 4
d. number of poles is 2
Q. In a D.C. generator in order to reduce sparking at brushes, the self-induced e.m.f. in the coil is neutralised by all of the following except
a. interpoles
b. dummy coils
c. compensating winding
d. shifting of axis of brushes
Q. To achieve sparkless commutation brushes of a D.C. generator are rockedmahead soas to bring them
a. just ahead of magnetic neutral axis
b. in magnetic neutral axis
c. just behind the magnetic neutral axis
d. none
Q. 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
Q. A cumulatively compounded long shunt generator when operating as a motor would be
a. cumulatively compounded long shunt
b. differentially compounded long shunt
c. cumulatively compounded short shunt
d. differentially compounded short shunt
Q. In any rotating machine that part which houses the conductors and in which e.m.f.induced is to be utilised is called
a. rotor
b. stator
c. field
d. armature
Q. In a D.C. machine stray loss is the sum of
a. total copper loss and mechanical loss
b. armature copper loss and iron loss
c. shunt field copper loss and mechanical loss
d. iron loss and mechanical loss
Q. Lap winding is composed of
a. any even number of conductors
b. any odd number of conductors
c. that even number which is exact multiple of poles + 2
d. that even number which is exact multiple of poles