1
GATE EE 2004
+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%
2
GATE EE 2004
+2
-0.6
A 8 pole, DC generator has a simplex wave-wound armature containing 32 coils of 6 turns each. Its flux per pole is 0.06 Wb. The machine is running at 250 rpm. The induced armature voltage is
A
96V
B
192V
C
384V
D
768V
3
GATE EE 2004
+2
-0.6
The resistance and reactance of a 100 kVA 11000|400 V, $$\triangle$$ - Y distribution transformer are 0.02 and 0.07 pu respectively. The phase impedance of the transformer referred to the primary is
A
(0.02 + j0.07) Ω
B
(0.55 + j1.925) Ω
C
(15.125 + j52.94) Ω
D
(72.6 + j254.1) Ω
4
GATE EE 2004
+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%
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