1
GATE EE 2011
MCQ (Single Correct Answer)
+2
-0.6
The direct axis and quadrature axis reactances of a salient pole alternator are $$1.2$$ $$p.u$$ and $$1.0$$ $$p.u$$ respectively. The armature resistance is negligible. If this alternator is delivering rated $$kVA$$ at $$upf$$ and at rated voltage then its power angle is
A
$${30^ \circ }$$
B
$${45^ \circ }$$
C
$${60^ \circ }$$
D
$${90^ \circ }$$
2
GATE EE 2010
MCQ (Single Correct Answer)
+2
-0.6
A $$50$$ $$Hz$$ synchronous generator is initially connected to a long lossless transmission line which is open circuited at the receiving end. With the field voltage held constant, the generator is disconnected from the transmission line. Which of the following may be said about the steady state terminal voltage and field current of the generator?
A
The magnitude of terminal voltages decreases, and the field current does not change.
B
The magnitude of terminal voltage increases, and the field current dose not change.
C
The magnitude of terminal voltages decreases, and the field current increases.
D
The magnitude of terminal voltage does not change, and the field current decreases.
3
GATE EE 2010
MCQ (Single Correct Answer)
+2
-0.6
A separately excited $$dc$$ machine is coupled to a $$50Hz,$$ three-phase, 4-pole induction machine as shown in the figure. The dc machine is energized first and the machines rotate at $$1600$$ $$rpm.$$ Subsequently the induction machine is also connected to a $$50Hz,$$ three-phase source, the phase sequence being consistent with the direction of rotation. In steady state GATE EE 2010 Electrical Machines - Synchronous Machines Question 24 English
A
both machine act as generators
B
the $$dc$$ machine acts as a generator, and the induction machine acts as a motor
C
the $$dc$$ machine acts as a motor, and the induction machine acts as a generator
D
both machines act as motors
4
GATE EE 2009
MCQ (Single Correct Answer)
+2
-0.6
A field excitation of $$20A$$ in a certain alternator results in a armature current of $$400$$ $$A$$ in short circuit and a terminal voltage of $$2000$$ $$V$$ on open circuit. The magnitude of the internal voltage drop with in the machine at a load current of $$200$$ $$A.$$
A
$$1$$ $$V$$
B
$$10$$ $$V$$
C
$$100$$ $$V$$
D
$$1000$$ $$V$$
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