Which of the following steps is likely to result in reduction of hysteresis loss in a D.C. generator ?
Using non-magnetic material for frame
Providing laminations in stator
Providing laminations in armature core
Using material of low hysteresis co-efficient for armature core material
Using material of low hysteresis co-efficient for armature core material
Which of the following loss in a D.C. generator is dissipated in the form of heat?
Mechanical loss
Core loss
All of the above
Copper loss
All of the above
The total losses in a well designed D.C. generator of 10 kW will be nearly
500 W
1500 W
1000 W
100 W
500 W
The condition for maximum efficiency for a D.C. generator is
variable losses = constant losses
hysteresis losses = eddy current losses
eddy current losses = stray losses
copper losses = 0
variable losses = constant losses
In a D.C. generator the iron losses mainly take place in
armature conductors
armature rotor
yoke
commutator
armature rotor
D.C. generators are normally designed for maximum efficiency around
full-load
rated r.p.m.
rated voltage
all of the above
full-load
Regenerative method of braking is based on that
none of the above
back e.m.f. of rotor is more than the applied voltage
back e.m.f. is less than the applied voltage
back e.m.f. is equal to the applied voltage
back e.m.f. is equal to the applied voltage
D.C. generators are installed near the load centres to reduce
iron losses
sparking
line losses
corona losses
line losses
The purpose of retardation test on D.C. shunt machines is to find out
stray losses
windage losses
field copper losses
eddy current losses
stray losses
Hopkinson’s test on D.C. machines is conducted at
full-load
part load
no-load
overload
full-load
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