Multiple Choice Questions in Power Systems - 2
Important multiple choice questions in Power systems
1.
The good effect of corona on overhead lines is
to
A)
Increase the line carrying capacity due to
conducting ionized air envelop around the conductor
B)
Increase the power factor due to corona loss
C)
Reduce the radio interference from the conductor
D)
Reduce the steepness of
surge fronts
2.
The principal information obtained from load
flow studies in a power system are
I.
Magnitude and phase angle of the voltage at each
bus
II.
Reactive and real power flows in each of the lines
III.
Total power loss in the network
IV.
Transient stability limit of the system
Select the correct answer using the codes given below:
A)
1 and 2
B)
3 and 4
C)
1,2 and 3
D)
2 and 4
3.
Three generators rated 100 MVA, 11 kV have an
impedance of 0.15 pu each. If in the same plant, these generators are being
replaced by a single equivalent generator, the effective impedance of
equivalent generator will be
A)
0.05 pu
B)
0.15 pu
C)
0.25 pu
D)
0.45 pu
4.
If all the sequence voltages at the fault point
in a power system are equal, then the fault is a
A)
Three-phase fault
B)
Line to ground fault
C)
Line to line fault
D)
Double line to ground
fault
5.
Which one of the following relays has the
capability of anticipating the possible major fault in the transformer?
A)
Overcurrent relay
B)
Differential relay
C)
Buchholz relay
D)
Overfluxing relay
6.
In a 220kV system, the inductance and
capacitance up to the circuit breaker location are 25mH and 0.025µF
respectively. The value of resistor required to be connected across the breaker
contacts which will give no transient oscillations, is
A)
25Ω
B)
250Ω
C)
500Ω
D)
1000Ω
7.
The speed regulation parameter R of a control
area is 0.025 HZ/MW and load frequency constant D is 2 MW/Hz. The area
frequency response characteristics (AFRC) is
A)
42 MW/Hz
B)
40 MW/Hz
C)
20 MW/Hz
D)
2 MW/Hz
8.
In the HVDC system, the ac harmonics which gets
effectively eliminated with 12 pulse bridge converters, are
A)
Triplen harmonics
B)
Triplen and fifth harmonics
C)
Triplen, fifth and seventh harmonics
D)
Fifth and seventh
harmonics
9.
The per-unit impedance of a circuit element of
0.15. if the base kV and base MVA are halved, then the new value of the
per-unit impedance of the circuit element will be
A)
0.075
B)
0.15
C)
0.30
D)
0.60
10.
The per-unit impedance of an alternator
corresponding to base values 13.2 kV and 30 MVA is 0.2 pu. The p.u. value of
the impedance for base values 13.8 kV and 50 MVA in p.u. will be
A)
0.131
B)
0.226
C)
0.305
D)
0.364
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