1
GATE EE 2002
Subjective
+5
-0
A $$230V,$$ $$250$$ $$rpm.$$ $$100A$$ separately excited $$dc$$ motor has an armature resistance of $$0.5\,\Omega .$$ The motor is connected to $$230V$$ $$dc$$ supply and rated $$dc$$ voltage is applied to the field winding. It is driving a load whose torque speed characteristic is given by $${T_L} = 500$$$$ - 10\omega ,$$ where $$\omega $$ is the rotational speed expressed in $$rad/sec$$ and $${T_L}$$ is the load torque in $$Nm.$$ Find the steady state speed at which the motor will drive the load and the armature current drawn by it from the source. Neglect the rotational losses of the machine.
2
GATE EE 2002
MCQ (Single Correct Answer)
+1
-0.3
If a 400 V, 50 Hz, star connected, 3 phase squirrel cage induction motor is operated from a 400 V, 75 Hz supply, the torque that the motor can now provide while drawing rated current from the supply?
A
reduces
B
increases
C
remains the same
D
increase or reduces depending upon the rotor resistance
3
GATE EE 2002
MCQ (Single Correct Answer)
+2
-0.6
A 400V/200V/200V, 50 Hz three winding transformer is connected as shown in Figure. The reading of the voltmeter 'V' will be GATE EE 2002 Electrical Machines - Transformers Question 51 English
A
0 V
B
400 V
C
600 V
D
800 V
4
GATE EE 2002
MCQ (Single Correct Answer)
+1
-0.3
A 1 kVA, 230V/100V, single phase, 50 Hz transformer having negligible winding resistance and leakage inductance is operating under saturation, while 250 V, 50 Hz sinusoidal supply is connected to the high voltage winding. A resistive load is connected to the low voltage winding which draws rated current. Which one of the following quantities will not be sinusoidal?
A
Voltage induced across the low voltage winding
B
Core flux
C
Load current
D
Current drawn from the source
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