1
GATE EE 2008
MCQ (Single Correct Answer)
+2
-0.6
A single phase full bridge converter supplies a load drawing constant and ripple free load current. If the triggering angle is $${30^ \circ },$$ the input power factor will be
A
$$0.65$$
B
$$0.78$$
C
$$0.85$$
D
$$0.866$$
2
GATE EE 2008
MCQ (Single Correct Answer)
+1
-0.3
A 3-phase transmission line is shown in figure: GATE EE 2008 Power System Analysis - Symmetrical Components and Symmetrical and Unsymmetrical Faults Question 43 English

Voltage drop across the transmission line is given by the following equation: $$$\left[ {\matrix{ {\Delta {V_a}} \cr {\Delta {V_b}} \cr {\Delta {V_c}} \cr } } \right] = \left[ {\matrix{ {{Z_s}} & {{Z_m}} & {{Z_m}} \cr {{Z_m}} & {{Z_s}} & {{Z_m}} \cr {{Z_m}} & {{Z_m}} & {{Z_s}} \cr } } \right]\left[ {\matrix{ {{i_a}} \cr {{i_b}} \cr {{i_c}} \cr } } \right]$$$
Shunt capacitance of the line can be neglect. If the line has positive sequence impedance of $$15\,\,\Omega $$ and zero sequence in impedance of $$48\,\,\Omega ,$$ then the values of $${{Z_s}}$$ and $${{Z_m}}$$ will be

A
$${Z_s} = 31.5\,\Omega ;\,\,{Z_m} = 16.5\,\Omega $$
B
$${Z_s} = 26\,\Omega ;\,\,{Z_m} = 11\,\Omega $$
C
$${Z_s} = 16.5\,\Omega ;\,\,{Z_m} = 31.5\,\Omega $$
D
$${Z_s} = 11\,\Omega ;\,\,{Z_m} = 26\,\Omega $$
3
GATE EE 2008
MCQ (Single Correct Answer)
+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.
4
GATE EE 2008
MCQ (Single Correct Answer)
+2
-0.6
A lossless power system has to serve a load of $$250$$ $$MW.$$ There are two generators ($$G1$$ and $$G2$$) in the system with cost curves $${C_1}$$ and $${C_2}$$ respectively defined as follows:
$${C_1}\left( {{P_{G1}}} \right) = {P_{G1}} + 0.055 \times P_{G1}^2$$
$${C_2}\left( {{P_{G2}}} \right) = 3{P_{G2}} + 0.03 \times P_{G2}^2$$
Where $${P_{G1}}$$ and $${P_{G2}}$$ are the MW injections from generator $${G_1}$$ and $${G_2}$$ respectively. Thus, the minimum cost dispatch will be
A
$${P_{G1}} = 250\,MW;\,\,{P_{G2}} = 0\,MW$$
B
$${P_{G1}} = 150\,MW;\,\,{P_{G2}} = 100\,MW$$
C
$${P_{G1}} = 100\,MW;\,\,{P_{G2}} = 150\,MW$$
D
$${P_{G1}} = 0\,MW;\,\,{P_{G2}} = 250\,MW$$