1
GATE EE 2004
MCQ (Single Correct Answer)
+1
-0.3
The direction of rotation of a 3-phase induction motor is clockwise when it is supplied with 3-phase sinusoidal voltage having phase sequence A-B-C. For counter clockwise rotation of the motor, the phase sequence of the power supply should be
A
B-C-A
B
C-A-B
C
A-C-B
D
B-C-A or C-A-B
2
GATE EE 2004
MCQ (Single Correct Answer)
+2
-0.6
A 500 kVA, 3-phase transformer has iron loses of 300 W and full load copper losses of 600 W. The percentage load at which the transformer is expected to have maximum efficiency is
A
50.0%
B
70.7%
C
141.4%
D
200.0%
3
GATE EE 2004
MCQ (Single Correct Answer)
+2
-0.6
The armature resistance of a permanent magnet dc motor is 0.8 $$\Omega$$. At no load, the motor draws 1.5 A from a supply voltage of 25 V and runs at 1500 rpm. The efficiency of the motor while it is operating on load at 1500 rpm drawing a current of 3.5 A form the same source will be
A
48.0%
B
57.1%
C
59.2%
D
88.8%
4
GATE EE 2004
MCQ (Single Correct Answer)
+1
-0.3
For a linear electromagnetic circuit, the following statement is true.
A
Field energy is equal to the co-energy
B
Field energy is greater than the co-energy
C
Field energy is lesser than the co-energy
D
Co-energy is zero