D.C Generator: [ ISRO,DRDO,DMRC,SAIL, ODNANCE, HAL, WBSEDCL, RAILWAY & Others competitive]
81. Which of the following generating machine will offer constant voltage on all loads?
(a) Self-excited generator
(b) Separately excited generator
(c) Level compounded generator.
(d) All of the above
Ans: c
82. Which of the following generators will be preferred if they are required to be run in parallel?
(a) Shunt generators
(b) Series generators
(c) Compound generators
(d) None of the above
Ans: a
83. Two generators are running in parallel. One of the generators may run as motor for which of the following reasons?
(a) The direction of that generator is reversed
(b) The speed of that generator is increased
(c) The field of that generator is weakened
(d) That generator takes large share of loads
55
Ans: b
84. A D.C. generator works on the principle of
(a) Lenz’s law
(b) Ohm’s law
(c) Faraday’s law of electromagnetic induction
(d) none of the above
Ans: c
85. A series generator can self-excite
(a) only if the load current is zero
(b) only if the load current is not zero
(c) irrespective of the value of load current
(d) none of the above
Ans: b
86. A shunt generator can self-excite
(a) only if the resistance of the field circuit is less than
critical value
(b) only if the resistance of the field circuit is greater than
critical value
(c) irrespective of the value of the resistance in the field
circuit
Ans: a
87. The terminal voltage of a series generator is 150 V when the load current is 5 A. If the load current is increased to 10 A, the terminal voltage will be
(a) 150 V
(b) less than 150 V
(c) greater than 150 V
(d) none of the above
Ans: c
88. The open circuit voltage of a compound generator is 250 V. At full load the terminal voltage
(a) will be less than 250 V
(b) will always be 250 V
(c) may be greater or less than 250 V
(d) none of the above
Ans: c
89. Two D.C. shunt generators, each with armature resistance of 0.02 ohm and field resistance of 50 ohm run in parallel and supply a total current of 1000 amperes to the load circuit. If their e.m.fs. are 270 V and 265 V, their bus bar voltage will be?
(a) 270 V
(b) 267.5 V
(c) 265 V
(d) 257.4 V
Ans: b
90. The essential condition for parallel operation of two D.C. generators is that they have ‘
(a) same kW rating
(b) the same operation r.p.m.
(c) the same drooping voltage characteristics
(d) same percentage regulation
Ans: c
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