For both lap and wave windings, there are as many commutator bars as the number of_____________?
A. slots
B. armature conductors
C. winding elements
D. poles
D.C. Generators
Wave winding is composed of_______________?
Wave 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
The number of armature parallel paths in a two-pole D.C. generator having duplex lap winding is______________?
The number of armature parallel paths in a two-pole D.C. generator having duplex lap winding is______________?
A. 2
B. 4
C. 6
D. 8
In a D.C. generator:___________________?
In a D.C. generator:___________________?
A. external resistance = internal char-acteristic – armature reaction
B. internal characteristic = magnetisation characteristic – ohmic drop
C. external characteristic = magnetisation characteristic – ohmic drop – armature reaction
D. magnetisation characteristic = external characteristic
In a D.C. generator the critical resistance can be increased by_____________?
In a D.C. generator the critical resistance can be increased by_____________?
A. increasing its field resistance
B. decreasing its field resistance
C. increasing its speed
D. decreasing its speed
Which generator would you prefer for feeding long D.C. transmission lines ?
Which generator would you prefer for feeding long D.C. transmission lines ?
A. Series generator
B. Shunt generator
C. Over compound generator
D. Flat compound generator
Following energized winding of a D.C. machine should not be opened as it would produce high inductive voltage which may be dangerous to personnel and may cause its own insulation failure.
Following energized winding of a D.C. machine should not be opened as it would produce high inductive voltage which may be dangerous to personnel and may cause its own insulation failure.
A. Series field
B. Compensating field
C. Inter pole field
D. Shunt field
Armature reaction in a generator results in_____________?
Armature reaction in a generator results in_____________?
A. demagnetisation of leading pole tip and magnetisation of trailing pole tip
B. demagnetisation of trailing pole tip and magnetisation of leading pole tip
C. damagnetising the center of all poles
D. magnetising the center of all poles
If residual magnetism is present in a D.C. generator, the induced e.m.f. at zero speed will be____________?
If residual magnetism is present in a D.C. generator, the induced e.m.f. at zero speed will be____________?
A. zero
B. small
C. the same as rated voltage
D. high
The purpose of providing dummy coils in a generator is__________________?
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