Multiple Choice Questions on Power Systems - 7
Important Multiple Choice questions on Power Systems
1.
For transmission line which one of the following
relations is true?
A)
AD-BC=1
B)
–AD-BC=1
C)
AD-BC=-1
D)
AD-BC=0
2.
For a given base voltage and base volt-amp, the
per unit impedance value of an element is X. what will be the per-unit
impedance value of this element when the voltage and volt-amp bases are both
doubled?
A)
4X
B)
2X
C)
X
D)
0.5X
3.
A 3-phase transmission line has its conductors
at the corners of an equilateral triangle with side 3m. the diameter of each
conductor is 1.63 cm. the inductance of the line per phase per km is
A)
1.232 mH
B)
1.182 mH
C)
1.093 mH
D)
1.043 mH
4.
A cable has inductance of 0.22mH per km and
capacitance of 0.202 micro farads per km. the surge impedance of the cable is
A)
28 ohms
B)
33 ohms
C)
42 ohms
D)
50 ohms
5.
The capacitance of an overhead transmission line
increases with
I.
Increase in mutual geometrical mean distance
II.
Increase in height of conductors above ground
Select the correct answer from the following?
A)
Both I and II are true
B)
Both I and II are false
C)
Only 1 is true
D)
Only 2 is true
6.
Consider the following statements
Addition of lumped capacitances in parallel
to a loss-free transmission line increases
I.
Characteristic impedance
II.
Propagation constant
III.
System stability
IV.
Charging current
Which of these statements are correct?
A)
I and III
B)
II and IV
C)
II,III and IV
D)
I, II and IV
7.
In multimachine interconnected system,
subsequent to a 3-phase fault, the transient stability is examined by
A)
Equal-area criterion
B)
Solution of swing
equation
C)
Either by equal-area criterion or by solution of
swing equation
D)
Combination of equal-area criterion and solution
of swing equation
8.
The electrical stiffness of a synchronous
generator connected to a very large grid can be increased by
A)
Increasing the excitation or the power angle of
the machine
B)
Reducing the excitation or the synchronous
reactance of the machine
C)
Increasing the synchronous reactance of the
machine
D)
Operating the generator
at a much lower MW level compared to the steady-state limit
9.
A surge of 100kV travels along an overhead line
towards its junction with a cable. The surge impedance for the overhead line
and cable are 400 ohms and 50 ohms respectively. The magnitude of the surge
transmitted through the cable
A)
11.11 kV
B)
22.22 kV
C)
12.50 kV
D)
88.89 kV
10.
A generated station has a maximum demand of
30MW, a load factor of 60% and plant capacity factor of 50%. The reserve
capacity of the plant is
A)
5MW
B)
4MW
C)
6MW
D)
10MW
Comments
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