1
GATE EE 2015 Set 2
+2
-0.6
A $$3$$-phase transformer rated for $$33 kV/11kV$$ is connected in delta/star as shown in figure. The current transformers $$\left( {C{T_s}} \right)$$ on low and high voltage sides have a ratio of $$500/5.$$ Find the currents $${i_1}$$ and $${i_2}$$, if the fault current is $$300$$ $$A$$ as shown in figure.
A
$${i_1} = {1 \over {\sqrt 3 }}A,\,\,{i_2} = 0\,A$$
B
$${i_1} = 0\,A,\,\,{i_2} = 0\,A$$
C
$${i_1} = 0\,A,\,\,{i_2} = {1 \over {\sqrt 3 }}A$$
D
$${i_1} = {1 \over {\sqrt 3 }}A,\,\,{i_2} = {1 \over {\sqrt 3 }}A$$
2
GATE EE 2014 Set 1
Numerical
+2
-0
The over current relays for the line protection and loads connected at the buses are shown in the figure.

The relays are IDMT is natural having the characteristic
$${t_{op}} = {{0.14\, \times \,time\,\,multiplier\,\,setting} \over {{{(plug\,\,setting\,\,multiplier)}^{0.02}} - 1}}$$
The maximum and minimum fault current at bus $$B$$ are $$2000A$$ and $$500$$ $$A$$ respectively. Assuming the time multiplier setting and plug setting for relay $${R_B}$$ to be $$0.1$$ and $$5$$ $$A$$ respectively, the operating time of $${R_B}$$ (in seconds) is __________.

3
GATE EE 2010
+2
-0.6
Consider a stator winding of an alternator with an internal high resistance ground fault. The currents under the fault condition are as shown in the figure. The winding is protected using a differential current scheme with current transformers of ratio $$400/5$$ $$A$$ as shown. The current through the operating coil is
A
$$0.1875$$ $$A$$
B
$$0.2$$ $$A$$
C
$$0.375$$ $$A$$
D
$$60$$ $$kA$$
4
GATE EE 2009
+2
-0.6
Match the items in List-$$I$$ (Type of transmission line) with the items in List-$$II$$ (Type of distance relay preferred) and select the correct answer using the codes below the lists.

List-$$I$$
$$A.$$ Short Line
$$B.$$ Mesium Line
$$C.$$ Long Line

List-$$II$$
$$1.$$ Ohm Relay
$$2.$$ Reactance Relay
$$3.$$ Mho Relay

A
$$A = 2,\,\,B = 1,\,\,C = 3$$
B
$$A = 3,\,\,B = 2,\,\,C = 1$$
C
$$A = 1,\,\,B = 2,\,\,C = 3$$
D
$$A = 1,\,\,B = 3,\,\,C = 2$$
EXAM MAP
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