1
GATE EE 2006
MCQ (Single Correct Answer)
+2
-0.6
A $$3$$-phase $$4000$$ $$V,$$ $$5$$ $$kW,$$ star connected synchronous motor having an internal reactance of $$10$$ $$ohms$$ is operating at $$50\% $$ load, unity power factor. Now, the excitation is increased by $$1\% $$, what will be the new load in percent, if the power factor is to be kept same? Neglect all losses and consider linear magnetic circuit.
A
$$67.9\% $$
B
$$56.9\% $$
C
$$51\% $$
D
$$50\% $$
2
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
$$1.06$$
3
GATE EE 2006
MCQ (Single Correct Answer)
+2
-0.6
Two transformers are to be operated in parallel such that they share load in proportion to their $$kVA$$ ratings. The rating of the first transformer is $$500$$ $$kVA$$ and its $$pu$$ leakage impedance is $$0.05$$ $$pu.$$ If the rating of second transformer is $$250$$ $$kVA,$$ its $$pu$$ leakage impedance is
A
$$0.20$$
B
$$0.10$$
C
$$0.25$$
D
$$0.025$$
4
GATE EE 2006
MCQ (Single Correct Answer)
+1
-0.3
In a $$DC$$ machine, which of the following statements is true?
A
Compensating winding is used for neutralizing armature reaction while inter pole winding is used for producing residual flux.
B
Compensating winding is used for neutralizing armature reaction while inter pole winding is used for improving commutation.
C
Compensating winding is used of improving commutation while inter pole winding is used for neutralizing armature reaction.
D
Compensating winding is used for improving commutation while inter pole winding is used for producing residual flux .