1
GATE EE 2003
MCQ (Single Correct Answer)
+2
-0.6
When Stator and Rotor windings of a 2-pole rotating electrical machine are
excited, each would produce a sinusoidal mmf distribution in the air gap with
peak values Fs and Fr respectively. The rotor mmf lags stator mmf by a space
angle $$\delta\;$$ at any instant as shown in Fig. Thus, half of stator and rotor surfaces
will form one pole with the other half forming the second pole. Further, the
direction of torque acting on the rotor can be clockwise or counter-clockwise.
The following Table gives four sets of statements as regards poles and torque.
Select the correct set corresponding to the mmf axes as shown in Figure.
2
GATE EE 2003
MCQ (Single Correct Answer)
+2
-0.6
A single phase induction motor with only the main winding excited would exhibit
the following response at synchronous speed
3
GATE EE 2003
MCQ (Single Correct Answer)
+2
-0.6
A 3-phase Inductor Motor is driving a constant torque load at rated voltage and
frequency. If both voltage and frequency are halved, following statements relate
to the new condition if stator resistance, leakage reactance and core loss are
ignored.
P. The difference between synchronous speed and actual speed remains same
Q. The air-gap flux remains same
R. The stator current remains same
S. The p.u. slip remains same
Among the above, correct statements are
P. The difference between synchronous speed and actual speed remains same
Q. The air-gap flux remains same
R. The stator current remains same
S. The p.u. slip remains same
Among the above, correct statements are
4
GATE EE 2003
MCQ (Single Correct Answer)
+2
-0.6
Following are some of the properties of rotating electrical machines
P. Stator winding current is dc, rotor-winding current is ac
Q. Stator winding current is ac, rotor-winding current is dc
R. Stator winding current is ac, rotor-winding current is ac
S. Stator has salient poles and rotor has commutator
T. Rotor has salient poles and sliprings and stator is cylindrical
U. Both stator and rotor have poly-phase windings
P. Stator winding current is dc, rotor-winding current is ac
Q. Stator winding current is ac, rotor-winding current is dc
R. Stator winding current is ac, rotor-winding current is ac
S. Stator has salient poles and rotor has commutator
T. Rotor has salient poles and sliprings and stator is cylindrical
U. Both stator and rotor have poly-phase windings
DC machines. Synchronous machines and Induction machines exhibit some of the above properties as given in the following table. Indicate the correct combination from this table
Questions Asked from Induction Machines (Marks 2)
Number in Brackets after Paper Indicates No. of Questions
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GATE EE 2005 (4)
GATE EE 2004 (3)
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GATE EE Subjects
Electric Circuits
Electromagnetic Fields
Signals and Systems
Electrical Machines
Engineering Mathematics
General Aptitude
Power System Analysis
Electrical and Electronics Measurement
Analog Electronics
Control Systems
Power Electronics