1
GATE EE 2006
MCQ (Single Correct Answer)
+2
-0.6
A $$220V$$ $$DC$$ machine supplies $$20$$ $$A$$ at $$200V$$ as a generator. The armature resistance is $$0.2$$ ohm. If the machine is now operated as a motor at same terminal voltage and current but with the flux increased by $$10\% ,$$ the ratio of motor speed to generator speed is
A
$$0.87$$
B
$$0.95$$
C
$$0.96$$
D
$$1.06$$
2
GATE EE 2005
MCQ (Single Correct Answer)
+2
-0.6
Two magnetic poles revolve around a stationary armature carrying two coils ($$c_1-c'_1$$ , $$c_2-c'_2$$ ) as shown in Figure. Consider the instant when the poles are in a position as shown. Identify the correct statement regarding the polarity of the induced emf at this instant in coil sides $$c_2$$ and $$c_1$$. GATE EE 2005 Electrical Machines - D.C Machines Question 56 English
A
$$\odot\;in\;c_1$$, no emf in c2
B
$$\otimes\;in\;c_1$$, no emf in c2
C
$$\odot\;in\;c_2$$, no emf in c1
D
$$\otimes\;in\;c_2$$, no emf in c1
3
GATE EE 2005
MCQ (Single Correct Answer)
+2
-0.6
A 50 kW dc shunt motor is loaded to draw rated armature current at any given speed. When driven
(i) at half the rated speed by armature voltage control and
(ii) at 1.5 times the rated speed by field control, the respective output powers delivered by the motor are approximately
A
25 kW in (i) and 75 kW in (ii)
B
25 kW in (i) and 50 kW in (ii)
C
50 kW in (i) and 75 kW in (ii)
D
50 kW in (i) and 50 kW in (ii)
4
GATE EE 2005
MCQ (Single Correct Answer)
+2
-0.6
In relation to DC machines, match the following and choose the correct combination.

Group-I(Performance variables)
(P) Armature emf (E)
(Q) Developed torque (T)
(R) Developed power (P)

Group-II(Proportional to)
1.Flux ($$\phi$$), speed ($$\omega$$) and armature current ($$I_a$$)
2.$$\phi$$ and $$\omega$$ only
3.$$\phi$$ and $$I_a$$ only
4.$$I_a$$ and $$\omega$$ only
5.$$I_a$$ only

A
$$\begin{array}{l}P\;\;\;\;Q\;\;\;\;R\\3\;\;\;\;\;3\;\;\;\;\;1\end{array}$$
B
$$\begin{array}{l}P\;\;\;\;Q\;\;\;\;R\\2\;\;\;\;\;5\;\;\;\;\;4\end{array}$$
C
$$\begin{array}{l}P\;\;\;\;Q\;\;\;\;R\\3\;\;\;\;\;5\;\;\;\;\;4\end{array}$$
D
$$\begin{array}{l}P\;\;\;\;Q\;\;\;\;R\\2\;\;\;\;\;3\;\;\;\;\;1\end{array}$$
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