91
|
What should be
width of radial ventilating ducts for DC machine?
|
92
|
Which are the
factors to be considered before selecting the length of air gap in the DC
machine?
|
There are following factors to be
considered before selecting the length of air gap
|
|
93
|
Describe the
effect of air gap on the armature reaction in the DC machine.
|
Air gap – Armature reaction
|
|
94
|
Describe the effect
of air gap on the pole face losses in the DC machine.
|
Air gap – Pole face losses
|
|
95
|
Describe the
effect of air gap on the circulating current of the DC machine.
|
The slight irregularity in the air gap
cause flow of large circulating current in the DC machine therefore the
length of air gap in the DC machine should be large.
|
|
96
|
What should be
value of armature mmf at pole center and center of inter polar axis?
|
The armature mmf is zero at pole
center and maximum at the center of the inter polar axis.
|
|
97
|
Why the flux
density at the inter polar axis is small?
|
The flux density in the inter polar
axis is small because the reluctance in this region is large due to large air
gap.
|
|
98
|
What should be
wave shape of armature mmf?
|
Symmetrical triangular
|
|
99
|
What should be
flux density at pole tips in the case of motor and generator?
|
Flux density at pole tips
|
|
100
|
What is value
of flux density in the magnetic neutral axis?
|
Zero
|
|
101
|
State the
other name of inter polar axis.
|
Geometrical neutral axis
|
|
102
|
Explain : The
effect of armature reaction is responsible delay commutation in the DC
machine.
|
Armature reaction – Delay commutation
|
|
103
|
Describe the
effect of armature reaction in the DC machine.
|
Effect of armature reaction
|
|
104
|
Why the iron
loss increases due to effect of armature reaction in the DC machine?
|
Armature reaction – Iron loss
|
|
105
|
What should be
voltage limit between adjacent segment of commutator?
|
30 V
|
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