1
GATE EE 2008
+2
-0.6
A $$240V$$ $$dc$$ shunt motor draws $$15A$$ while supplying the rated load at a speed of $$80$$ $$rad/s$$. The armature resistance is $$0.5$$ $$ohm$$ and the field winding resistance is $$80$$ $$ohm.$$

The external resistance to be added in the armature circuit to limit the armature current to $$125\%$$ of its rated value is

A
$$31.1$$ $$ohm$$
B
$$31.9$$ $$ohm$$
C
$$15.1$$ $$ohm$$
D
$$15.9$$ $$ohm$$
2
GATE EE 2008
+2
-0.6
A $$240V$$ $$dc$$ shunt motor draws $$15A$$ while supplying the rated load at a speed of $$80$$ $$rad/s$$. The armature resistance is $$0.5$$ $$ohm$$ and the field winding resistance is $$80$$ $$ohm.$$

The net voltage across the armature resistance at the time of plugging will be

A
$$6V$$
B
$$234$$ $$V$$
C
$$240$$ $$V$$
D
$$474$$ $$V$$
3
GATE EE 2006
+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
$$1.06$$
4
GATE EE 2005
+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 $$c_1$$.
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
EXAM MAP
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