# Power Systems (Test 3)

## Gate Exam : Ee Electrical Engineering

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Q.1
The bus admittance matrix for a power system network is pu
There is a transmission line, connected between buses 1 and 3, which is represented by the circuit shown in figure. If this transmission line is removed from service, What is the modified bus admittance matrix?
A. B. C. D. Explaination / Solution: Workspace
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Q.2
A single-phase load is supplied by a single-phase voltage source. If the current flowing from the load to the source is 10<− 150°A and if the voltage at the load terminals is 100<60°V , then the
A. load absorbs real power and delivers reactive power.
B. load absorbs real power and absorbs reactive power.
C. load delivers real power and delivers reactive power.
D. load delivers real power and absorbs reactive power.
Explaination / Solution:
No Explaination.

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Q.3
A source vs(t) = V cos 100πt has an internal impedance of (4 + j3)Ω. If a purely resistive load connected to this source has to extract the maximum power out of the source, its value in Ω should be
A. 3
B. 4
C. 5
D. 7
Explaination / Solution:
No Explaination.

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Q.4
Power is transferred from system A to system B by an HVDC link as shown in the figure. If the voltages VAB and VCD are as indicated in the figure, and I > 0, then A. VAB < 0, VCD < 0, VAB > VCD
B. VAB > 0, VCD > 0, VAB < VCD
C. VAB > 0, VCD > 0, VAB > VCD
D. VAB > 0, VCD < 0
Explaination / Solution:
No Explaination.

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Q.5
Consider a step voltage wave of magnitude 1pu travelling along a lossless transmission line that terminates in a reactor. The voltage magnitude across the reactor at the instant the travelling wave reaches the reactor is A. −1pu
B. 1pu
C. 2pu
D. 3pu
Explaination / Solution:
No Explaination.

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Q.6
Consider two buses connected by an impedance of (0+j5) Ω. The bus1 voltage is 100∠300 V, and bus2 voltage is 100∠00V. The real and reactive power supplied by bus 1, respectively, are
A. 1000 W, 268 VAr
B. −1000 W, −134 VAr
C. 276.9 W, −56.7 VAr
D. −276.9 W, 56.7 VAr
Explaination / Solution:
No Explaination.

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Q.7
When the Newton-Raphson method is applied to solve the equation f(x) = x3 + 2x – 1 = 0, the solution at the end of the first iteration with the initial guess value as x= 1.2 is
A. -0.82
B. 0.49
C. 0.705
D. 1.69
Explaination / Solution:
No Explaination.

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Q.8
A three-phase, 33kV oil circuit breaker is rated 1200 A, 2000 MVA, 3s. The symmetrical breaking current is
A. 1200 A
B. 3600 A
C. 35 kA
D. 104.8 kA
Explaination / Solution:
No Explaination.

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Q.9
The zero-sequence circuit of the three phase transformer shown in the figure is A. B. C. D. Explaination / Solution:
No Explaination.

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Q.10
For a power system network with n nodes, Z33 of its bus impedance matrix is j0.5 per unit. The voltage at node 3 is 1.3 ∠–10° per unit. If a capacitor having reactance of –j3.5 per unit is now added to the network between node 3 and the reference node, the current drawn by the capacitor per unit is
A. 0.325 ∠–100°
B. 0.325 ∠80°
C. 0.371 ∠–100°
D. 0.433 ∠80°