1
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 __________.

2
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
$$60$$ $$kA$$
3
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
$$A = 1,\,\,B = 3,\,\,C = 2$$
4
GATE EE 2008
+2
-0.6
Voltage phasors at the two terminals of a transmission line of length $$70$$ km have a magnitude of $$1.0$$ per unit but are $$180$$ degrees out of phase. Assuming that the maximum load current in the line is $$1/5$$th of minimum $$3$$-phase fault current. Which one of the following transmission line protection schemes will NOT pick up for this condition?
A
Distance protection using mho relays with zone-$$1$$ set to $$80$$% of the line impedance.
B
Directional over current protection set to pick up at $$1.25$$ times the maximum load current
C
Pilot relaying system with directional comparison scheme
D
Pilot relaying system with segregated phase comparison scheme.
GATE EE Subjects
Electromagnetic Fields
Signals and Systems
Engineering Mathematics
General Aptitude
Power Electronics
Power System Analysis
Analog Electronics
Control Systems
Digital Electronics
Electrical Machines
Electric Circuits
Electrical and Electronics Measurement
EXAM MAP
Joint Entrance Examination