1
GATE EE 2008
MCQ (Single Correct Answer)
+2
-0.6
A $$230V,$$ $$50Hz,$$ $$4$$ pole, single phase induction motor is rotating in the clockwise (forward) direction at a speed of $$1425$$ $$rpm.$$ If the rotor resistance at standstill is $$7.8\,\,\Omega ,$$ then the effective rotor resistance in the backward branch of the equivalent circuit will be
A
$$2\Omega $$
B
$$4\Omega $$
C
$$78\Omega $$
D
$$156\Omega $$
2
GATE EE 2008
MCQ (Single Correct Answer)
+2
-0.6
A synchronous motor is connected to an infinite bus at $$1.0$$ $$p.u$$ voltage and draws $$0.6$$ $$pu$$ at unity power factor. Its synchronous reactance is $$1.0$$ $$pu$$ and resistance is negligible.

The excitation voltage and load angle will respectively be

A
$$0.8$$ $$pu$$ and $$36.86$$ degrees lag
B
$$0.8$$ $$pu$$ and $$36.86$$ degrees lead
C
$$1.17$$ $$pu$$ and $$30.96$$ degrees lead
D
$$1.17$$ $$pu$$ and $$30.96$$ degrees lag
3
GATE EE 2008
MCQ (Single Correct Answer)
+2
-0.6
A synchronous motor is connected to an infinite bus at $$1.0p.u$$ voltage and draws $$0.6$$ $$pu$$ at unity power factor. Its synchronous reactance is $$1.0$$ $$pu$$ and resistance is negligible.

Keeping the excitation voltage same, the load on the motor is increased such that the motor current increases by $$20\% $$. The operating power factor will become

A
$$0.995$$ lagging
B
$$0.995$$ leading
C
$$0.791$$ lagging
D
$$0.848$$ leading
4
GATE EE 2008
MCQ (Single Correct Answer)
+1
-0.3
Distributed winding and short chording employed in AC machines will result in
A
increase in $$emf$$ and reduction in harmonics
B
reduction in $$emf$$ and increase in harmonics
C
increase in both $$emf$$ and harmonics
D
reduction in both $$emf$$ and harmonics
EXAM MAP