DC MACHINES MCQS 5
61) A dc series generator is provided with divertor
and is delivering its rated current.If the divertor switch is opened, the
terminal voltage will
a) remain constant b)
decrease c) increase d) none of these
ANS:C
62) A 4 pole, 25 kw, 200 v wave wound dc shunt
generator the current in each parallel path will be
a) 62.5 A b)
125 A c) 31.25 A d) 250 A
ANS:A
63) A dc shunt generator is supplying a load of 1.8
kw at 200 V. Its armature and field resistances are 0.4 ohms and 200 ohms
respectively. What is the generated emf>
a) 190 V b)
196 V c) 204 V d) 210 V
ANS:C
64) If the field circuit resistance of a dc shunt
generator exceeds its critical value, the generator
a) fails to build up b)
builds up a very high voltage
c) exceeds its current capacity d) produces power beyoud its rating
ANS:A
65) The factor that is not responsible for drop in
terminal voltage of a dc shunt generator on load is
a) commutation b)
armature reaction
c) armature resistance drop d) field weakening due to (b) and (c)
ANS:A
66) In a dc shunt generator, the voltage build up is
generally restricted due to
a) armature heating b)
insulation restrictions
c) saturation of iron d) speed limitation
ANS:C
67) An ideal dc generator has a regulation of ------
per cent
a) zero b)
10 c) 25 d) 100
ANS:A
68) The terminal voltage of an over compounded dc
generator
a) decreases with the increase in load current
b) increases with the increase in load current
c) remains constant at all load current
d) none of the above
ANS:B
69) In a dc compound generator, flat compound
characteristic, required for certain applications,may be obtained by connecting
a variable resistance
a) across the series field b) in series with the series field
c) in oarallel with the shunt field d) in series with the shunt field
ANS:A
70) A cumulatively compounded dc generator is
supplying 20 A at 200 V. Now if the series field winding is short circuited,
the terminal voltage
a) will remain unaltered at 200 V
b) will rise to 220 V
c) will shoot upto a very high value
d) will become less than 200 V
ANS:A
71) Over or under compounding of a dc generator is
achieved by
a) shunting more or less current from the shunt
field
b) shunting more or less current from the series
field
c) connecting its as long shunt
d) connecting its as short-shunt
ANS:B
72) An over-compounded dc generator is supplying 800
A at full load on 500 V. The resistance of each conductor is 0.02 ohm. The
percentage of compounding is
a) 1.6 % b)
3.2% c) 6.4% d) 12.8%
ANS:C
73) Which of the following dc generators will be in
a position to build up without any residual magnetism in the field?
a) series b)
shunt c) separately excited d) compound
ANS:C
74) Which of the following dc generators has rising
v-I characteristics?
a) series b)
shunt c) compound d) none
ANS:A
75) Which of the following dc generators will have
negligible terminal voltage on no load?
a) shunt b)
series c) compound d) none
ANS:B
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