Power Systems Questions and Answers – Parallel Circuit Three Phase Lines

This set of Power Systems Multiple Choice Questions & Answers (MCQs) focuses on “Parallel Circuit Three Phase Lines”.

1. Nominal-T and nominal-π are equivalent to each other.
a) True
b) False
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2. For the circuit representation of a transmission line below, the transmission line T-matrix will be ___________


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3. For the circuit representation of a transmission line below, the transmission line T-matrix will be . Then AB – CD value will be _________

a) Y
b) 1
c) -Y
d) 1-Y
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4. The transfer of the reactive power over a line mainly depends upon _____
a) Vr
b) Vs
c) |V_s| – |V_r|
d) Power angle
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5. For a medium transmission line system if the sending end line voltage is 143 kV with the line impedance as 101.24∠74° Ω and shunt admittance of 7.38*10-4∠90° Ω-1.Then the no load line voltage at the receiving end would be _________
a) 148.3 kV
b) 140.8 kV
c) 149.2 kV
d) 132 kV
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Answer: a

6. For a medium transmission line system if the sending end line voltage is 143 kV with the line impedance as 101.24∠74° Ω and shunt admittance of 7.38*10-4∠90° Ω-1 delivering 25 MVA at 0.8 power factor lagging in nature to the load at 132 kV. The voltage regulation is ___________
a) 12.3
b) 12.8
c) 14.2
d) -2.3
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Answer: a

Voltage regulation = (148.3-132)/132 = 12.3%.

7. For the lines more than 250 km, the parameters of a line are considered not ______ but _____
a) lumped, distributed
b) distributed, lumped
c) lumped, non uniform lumped
d) uniform, lumped
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8. Which of the parameters of a long transmission line and medium transmission lines are same?
a) A and D
b) B, C
c) Only A
d) Only D
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9. With 100% series compensation of the transmission lines, which of the following effects are observed?
(i) Low transient voltage
(ii) High transient current
(iii) The current is series resonant at power frequency
a) (ii), (iii)
b) (i), (ii)
c) (i), (ii), (iii)
d) (iii)
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10. With 100% series compensation of the transmission lines, which of the following effects are not observed?
(i) Low transient voltage
(ii) High transient current
(iii) The current is series resonant at power frequency
a) (ii), (iii)
b) (i)
c) (i), (ii), (iii)
d) (iii)
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11. Estimate the transmission line parameters (ABCD), for the given distributed network.


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Answer: a
Explanation: Vs= Z1*Is + Y^{-1*(Is+Ir)
Vr = Z2*Ir + Y-1*(Is+Ir)
VY = Is+Ir
Solving above equation, we get}

12. Estimate the transmission line parameters (ABCD), for the given distributed network and find AB-CD.

a) 1
b) Y
c) Y-Z1Z2
d) 0
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Answer: 1
Explanation: Vs= Z1*Is + Y^-1*(Is+Ir)
Vr = Z2*Ir + Y-1*(Is+Ir)
VY = Is+Ir
Solving above eq, we get

AD-BC = 1.

13. Estimate the transmission line parameters (ABCD), for the given distributed network.


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Answer: a
Explanation: Applying KVL in the middle loop and KCL at the two nodes, we will get

14. Surge impedance for 400ohms implies for a transmission line that ___________
a) line can be theoretically loaded up to 400ohms
b) line can be practically loaded up to 400ohms
c) open circuit impedance of 400ohms
d) short circuit impedance of 400ohms
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Sanfoundry Global Education & Learning Series – Power Systems.

To practice all areas of Power Systems, here is complete set of 1000+ Multiple Choice Questions and Answers.

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