Important MCQ on Power systems - 9

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1.       When a pumped storage power plant is operated in conjunction with a steam power plant
a.       The operating cost of the steam plant becomes optimum
b.      Load factor of the steam plant is increased
c.       Chances of the tripping of the system decreases because of the use of two heterogeneous types of plants
d.      Operation of the storage plant in the pumping mode during the low-load period improves the steam-plant stability
2.       Usage of materials in components of a nuclear reactor:
    Graphite is used in moderators; Boron is used in control rods ; Sodium is used as a coolant ; Concrete is used as a shield
3.       A 100km long transmission line is loaded at 110kV. If the loss of line is 15MW and the load is 150MVA, the resistance of the line is
a.       8.06 ohms per phase
b.      0.806 ohms per phase
c.       0.0806 ohm per phase
d.      80.6 ohms per phase
4.       Two insulator discs of identical capacitance value C make up string for a 22kV, 50Hz, single-phase overhead line insulation system. If the pin to earth capacitance is also C, then the string efficiency is
a.       50%
b.      75%
c.       90%
d.      86%
5.       Which one of the following statements is NOT correct for the use of bundled conductors in transmission lines?
a.       Control of voltage gradient
b.      Reduction in corona loss
c.       Reduction in radio interference
d.      Increase in interference with communication lines
6.       A power system consists of two areas connected via a tie line. While entering the data for load flow the tie line parameters and its connectivity data were inadvertently left out. If the load flow program is run with this incomplete data, then the load flow calculations will converge only if
a.       One slack bus is specified in the first area
b.      One slack bus is specified in the second area
c.       One slack bus is specified in either of the two areas
d.      Two slack buses, one in each area are specified
7.       The zero sequence current of a generator for line to ground fault is j2.4 p.u. then the current through the neutral during the fault is
a.       j2.4 p.u
b.      j 0.8 p.u
c.       j 7.2 p.u
d.      j 0.24 p.u
8.       in HVDC transmission there are predominant
a.       Voltage harmonics on DC side and current harmonics on AC side of converters
b.      Current harmonics on DC side and voltage harmonics on AC side of converters
c.       Current harmonics only on the DC side of Converters
d.      Voltage harmonics only on the AC side of converters
9.       Which one of the following statements is correct? Corona loss increase with
a.       Decrease in conductor size and increase in supply frequency
b.      Increase in both conductor size and supply frequency
c.       Decrease in both conductor size and supply frequency
d.      Increase in conductor size & decrease in supply frequency
10.   For affixed receiving end and sending end voltage in a transmission system, what is the locus of the constant power?
a.       A straight line
b.      An ellipse
c.       A parabola
d.      A circle

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