1
GATE EE 2001
MCQ (Single Correct Answer)
+2
-0.6
A 3-phase transformer has rating of 20 MVA, 220 kV (star) / 33 kV (delta) with leakage reactance of 12%. The transformer reactance (in ohms) referred to each phase of the L.V. delta-connected side is
A
23.5
B
19.6
C
18.5
D
8.7
2
GATE EE 2000
MCQ (Single Correct Answer)
+2
-0.6
A 3-phase delta/star transformer is supplied at 6000 V on the delta-connected side. The terminal voltage on the secondary side when supplying full load as 0.8 lagging power-factor is 415 V. The equivalent resistance and reactance drops for the transformer are 1% and 5% respectively. The turn's ratio of the transformer is:
A
14
B
24
C
42
D
20
3
GATE EE 1999
MCQ (Single Correct Answer)
+2
-0.6
A 400V/100V, 10 kVA two-winding transformer is reconnected as an autotransformer across a suitable voltage source. The maximum rating of such an arrangement could be
A
50 kVA
B
15 kVA
C
12.5 kVA
D
8.75 kVA
4
GATE EE 1999
MCQ (Single Correct Answer)
+2
-0.6
The windings of a Q kVA, $$\frac{V_1}{V_2}$$ Volt, three-phase, Delta connected, core type transformer are reconnected to work as a single phase transformer. The maximum voltage and the power ratings of the new configuration are,
A
$$\frac{3V_1}{3V_2},\;3Q$$
B
$$\frac{V_1}{V_2},\;Q/3$$
C
$$\frac{\sqrt3V_1}{\sqrt3V_2},\;2Q$$
D
$$\frac{\displaystyle\frac32V_1}{\displaystyle\frac32V_2},\;\frac Q2$$

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