D.C. generators are connected to the busbars or disconnected from them only under the floating condition
to avoid burning of switch contacts
all above
to avoid sudden loading of the prime mover
to avoid mechanical jerk to the shaft
all above
The purpose of providing dummy coils in a generator is
to provide mechanical balance for the rotor
to reduce eddy current losses
to enhance flux density
to amplify voltage
to provide mechanical balance for the rotor
Welding generator will have
duplex wave winding
delta winding
wave winding
lap winding
lap winding
In case of D.C. machine winding number of commutator segments is equal to
number of armature coil sides
number of armature conductors
number of armature coils
number of armature turns
number of armature coils
For a D.C. machines laboratory following type of D.C. supply will be suitable
induction motor D.C. generator set
synchronous motor D.C. generator set
mercury are rectifier
rotary converter
induction motor D.C. generator set
The function of pole shoes in the case of D.C. machine is
to discharge all the above functions
to spread out the flux to achieve uniform flux density
to reduce the reluctance of the mag¬netic path
to support the field coil
to discharge all the above functions
In the case of lap winding resultant pitch is
sum of front and back pitches
difference of front and back pitches
multiplication of front and back pitches
division of front pitch by back pitch
difference of front and back pitches
A D.C. welding generator has
lap winding
wave moving
duplex winding
any of the above
lap winding
In D.C. generators current to the external circuit from armature is given through
none of above
slip rings
solid connection
commutator
commutator
Brushes of D.C. machines are made of
soft copper
hard copper
carbon
all of above
carbon
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