1
GATE EE 2010
MCQ (Single Correct Answer)
+2
-0.6
A balanced star-connected and purely resistive load is connected at the secondary of a star-delta transformer as shown in the figure. The line-to-line voltage rating of the transformer is 110 V/220 V. Neglecting the non-idealities of the transformer, the impedance 'Z' of the equivalent star-connected load, referred to the primary side of the transformer, is GATE EE 2010 Electrical Machines - Transformers Question 58 English
A
(3 + j0) Ω
B
(0.866 − j0.5) Ω
C
(0.866 + j0.5) Ω
D
(1 + j0) Ω
2
GATE EE 2010
MCQ (Single Correct Answer)
+1
-0.3
A balanced three-phase voltage is applied to a star-connected induction motor, the phase to neutral voltage being V. The stator resistance, rotor resistance referred to the stator, stator leakage reactance, rotor leakage reactance referred to the stator, and the magnetizing reactance are denoted by $$r_s,\;r_r,\;r_s,\;r_r\;and\;X_m$$, respectively. The magnitude of the starting current of the motor is given by
A
$$\frac V{\sqrt{\left(r_s+r_r\right)^2+\left(x_s+x_r\right)^2}}$$
B
$$\frac V{\sqrt{r_s^2+\left(r_s+X_m\right)^2}}$$
C
$$\frac V{\sqrt{\left(r_s+r_r\right)^2+\left(X_m+x_r\right)^2}}$$
D
$$\frac V{\sqrt{r_s^2+\left(X_m+x_r\right)^2}}$$
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 27 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 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.
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