1
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
$$4\angle270^\circ$$
2
GATE EE 2014 Set 1
+2
-0.6
The core loss of a single phase, 230/115 V, 50 Hz power transformer is measured from 230 V side by feeding the primary (230 V side) from a variable voltage variable frequency source while keeping the secondary open circuited. The core loss is measured to be 1050 W for 230 V, 50 Hz input. The core loss is again measured to be 500W for 138 V, 30 Hz input. The hysteresis and eddy current losses of the transformer for 230 V, 50 Hz input are respectively.
A
508 W and 542 W
B
468 W and 582 W
C
498 W and 552 W
D
488 W and 562 W
3
GATE EE 2014 Set 3
+2
-0.6
The mean thickness and variance of silicon steel laminations are 0.2 mm and 0.02 respectively. The varnish insulation is applied on both the sides of the laminations. The mean thickness of one side insulation and its variance are 0.1 mm and 0.01 respectively. If the transformer core is made using 100 such varnish coated laminations, the mean thickness and variance of the core respectively are
A
30 mm and 0.22
B
30 mm and 2.44
C
40 mm and 2.44
D
40 mm and 0.24
4
GATE EE 2014 Set 3
+2
-0.6
The parameters measured for a 220V/110V, 50 Hz, single-phase transformer are:

Self inductance of primary winding = 45 mH
Self inductance of secondary winding = 30 mH
Mutual inductance between primary and secondary windings = 20 mH

Using the above parameters, the leakage (Ll1 , Ll2) and magnetizing (Lm) inductances as referred to primary side in the equivalent circuit respectively, are
A
5mH, 20mH and 40mH
B
5mH, 80mH and 40mH
C
25mH, 10mH and 20mH
D
45mH, 30mH and 20mH
EXAM MAP
Medical
NEET