Power Systems Questions and Answers – Symmetrical Component Transformation – 1

This set of Power Systems Multiple Choice Questions & Answers (MCQs) focuses on “Symmetrical Component Transformation – 1”.

1. The receiving end active power for a short transmission line is (where the angles have their usual meanings)
a) \(\frac{|V_s||V_r|}{|Z|} \cos(\theta – \delta) – \frac{|V_r|^2}{|Z|} \cos(\theta)\)
b) \(\frac{|V_s||V_r|}{|Z|} \sin(\theta – \delta) – \frac{|V_r|^2}{|Z|} \cos(\theta)\)
c) \(\frac{|V_s||V_r|}{|Z|} \sin(\theta – \delta) – \frac{|V_r|^2}{|Z|} \sin(\theta)\)
d) \(\frac{|V_s||V_r|}{|Z|} \cos(\theta + \delta) – \frac{|V_r|^2}{|Z|} \cos(\theta)\)
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2. The receiving end reactive power for a short transmission line is (where the angles have their usual meanings)
a) \(\frac{|V_s||V_r|}{|Z|} \cos(\theta – \delta) – \frac{|V_r|^2}{|Z|} \cos(\theta)\)
b) \(\frac{|V_s||V_r|}{|Z|} \sin(\theta – \delta) – \frac{|V_r|^2}{|Z|} \cos(\theta)\)
c) \(\frac{|V_s||V_r|}{|Z|} \sin(\theta – \delta) – \frac{|V_s|^2}{|Z|} \sin(\theta)\)
d) \(\frac{|V_s||V_r|}{|Z|} \cos(\theta + \delta) – \frac{|V_r|^2}{|Z|} \cos(\theta)\)
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3. The sending end active power for a 20 km transmission line with Vs as the sending end voltage and Vr as receiving end voltage, can be given by most appropriately
a) \(\frac{|V_s|^2}{|Z|} \cos(\theta) – \frac{|V_s||V_r|}{|Z|} \cos(\theta + \delta)\)
b) \(\frac{|V_r|^2}{|Z|} \cos(\theta) – \frac{|V_s||V_r|}{|Z|} \cos(\theta + \delta)\)
c) \(\frac{|V_s|^2}{|Z|} \cos(\theta) – \frac{|V_s||V_r|}{|Z|} \cos(\theta – \delta)\)
d) \(\frac{|V_s|^2}{|Z|} \sin(\theta) – \frac{|V_s||V_r|}{|Z|} \sin(\theta + \delta)\)
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4. The sending end reactive power for a 20 km transmission line with Vs as the sending end voltage and Vr as receiving end voltage, can be given by most appropriately
a) \(\frac{|V_s|^2}{|Z|} \cos(\theta) – \frac{|V_s||V_r|}{|Z|} \cos(\theta + \delta)\)
b) \(\frac{|V_r|^2}{|Z|} \cos(\theta) – \frac{|V_s||V_r|}{|Z|} \cos(\theta + \delta)\)
c) \(\frac{|V_s|^2}{|Z|} \cos(\theta) – \frac{|V_s||V_r|}{|Z|} \cos(\theta – \delta)\)
d) \(\frac{|V_s|^2}{|Z|} \sin(\theta) – \frac{|V_s||V_r|}{|Z|} \sin(\theta + \delta)\)
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5. The simplified ABCD representation of a 40 km transmission line is best given as
a) \(\begin{matrix}
1 & z \\
0 & 1
\end{matrix}\)
b) \(\begin{matrix}
1 & 0 \\
z & 1
\end{matrix}\)
c) \(\begin{matrix}
z & z \\
0 & 1
\end{matrix}\)
d) \(\begin{matrix}
1 & z \\
0 & z
\end{matrix}\)
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Answer: a
Explanation: From the given length, it is a short TL. Hence,

6. For a 35 km transmission line having a lumped impedance of the line as 20 ohms, is required to be shown in the ABCD form, it is given as
a) \(\begin{matrix}
1 & 20 \\
0 & 1
\end{matrix}\)
b) \(\begin{matrix}
1 & 0 \\
2 & 1
\end{matrix}\)
c) \(\begin{matrix}
1 & 0 \\
20 & 1
\end{matrix}\)
d) \(\begin{matrix}
20 & 0 \\
1 & 1
\end{matrix}\)
View Answer

Answer: a
Explanation: From the given length, it is a short TL. Hence,

7. If it is tried to represent the active and reactive power on a circle, then the radius would be
a) \(\frac{|V_s||V_r|}{|B|}\)
b) \(\frac{|V_s||V_r|}{|Z|} \sin \alpha\)
c) \(\frac{|V_s|^2}{|B|}\)
d) None of the mentioned
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Answer: a
Explanation:

8. The maximum power delivered to the load for short transmission line is at
a) β=α
b) β>α
c) β=δ
d) β>δ
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9. The maximum real active power delivered to the load is defined most accurately by
a) \(\frac{|V_s||V_r|}{|B|} – \frac{|V_r|^2 |D|}{|B|} \cos(\beta – \alpha)\)
b) \(\frac{|V_s||V_r|}{|B|} – \frac{|V_s|^2 |D|}{|B|} \cos(\beta – \alpha)\)
c) \(\frac{|V_s||V_r|}{|B|} – \frac{|V_r|^2 |D|}{|B|} \cos(\beta + \alpha)\)
d) \(\frac{|V_s||V_r|}{|D|} – \frac{|V_r|^2 |B|}{|D|} \cos(\beta – \alpha)\)
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10. For a given power system, its zero and maximum regulation will occur at the impedance angle of
a) 45
b) 90
c) 0
d) 60
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11. The charging currents due to shunt admittance can be neglected for ______ transmission line?
a) short
b) long
c) medium
d) all of the mentioned
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12. The transmission line equations are given by the below set of equations based on the line diagram as given. Identify the missing term marked as ’?’.
V_s = ?*V_r+B*I_r
I_s = C*V_r+D*I_r

a) 1+YZ
b) Z
c) Y
d) 1
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13. The transmission line equations are given by the below set of equations based on the line diagram as given. Identify the missing term marked as ’?’.
V_s = A*V_r+?*I_r
I_s = C*V_r+D*I_r

a) 1+YZ
b) Z
c) Y
d) 1
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14. The transmission line equations are given by the below set of equations based on the line diagram as given. Identify the missing term marked as ’?’.
V_s = A*V_r+B*I_r
I_s = ?*V_r+D*I_r

a) 1+YZ
b) Z
c) Y
d) 1
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15. The transmission line equations are given by the below set of equations based on the line diagram as given. Identify the missing term marked as ’?’.
V_s = A*V_r+B*I_r
I_s = C*V_r+?*I_r

a) 1+YZ
b) Z
c) Y
d) 1
View Answer

Sanfoundry Global Education & Learning Series – Power Systems.

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