1
GATE EE 2015 Set 2
+2
-0.6
A balanced (positive sequence) three-phase AC voltage source is connected to a balanced, star connected load through a star-delta transformer as shown in the figure. The line-to-line voltage rating is 230 V on the star side, and 115 V on the delta side. If the magnetizing current is neglected and $${\overline{\mathrm I}}_\mathrm s=100\angle0^\circ$$, then what is the value of $${\overline{\mathrm I}}_\mathrm p$$ in Ampere?
A
50$$\angle30^\circ$$
B
50$$\angle-30^\circ$$
C
50$$\sqrt3\angle30^\circ$$
D
200$$\angle30^\circ$$
2
GATE EE 2015 Set 2
+2
-0.6
A three-winding transformer is connected to an AC voltage source as shown in the figure. The number of turns are as follows: N1=100, N2=50, N3=50. If the magnetizing current is neglected, and the currents in two windings are $${\overline I}_2=2\angle30^\circ$$ A and $${\overline I}_3=2\angle30^\circ$$ A, then what is the value of the current $${\overline I}_1$$ in Ampere?
A
$$1\angle90^\circ$$
B
$$1\angle270^\circ$$
C
$$4\angle90^\circ$$
D
$$4\angle270^\circ$$
3
GATE EE 2015 Set 1
Numerical
+2
-0
Two single-phase transformers T1 and T2 each rated at 500 kVA are operated in parallel. Percentage impedances of T1 and T2 are (1 + j6) and (0.8 + j4.8), respectively. To share a load of 1000 kVA at 0.8 lagging power factor, the contribution of T2 (in kVA) is ________.
4
GATE EE 2015 Set 1
Numerical
+2
-0
A 200/400 V, 50 Hz, two-winding transformer is rated at 20 kVA. Its windings are connected as an auto-transformer of rating 200/600 V. A resistive load of 12 Ω is connected to the high voltage (600 V) side of the auto-transformer. The value of equivalent load resistance (in Ohm) as seen from low voltage side is _____.