Power Systems - II Mid - I, September - 2014
1.Bundle conductors in the EHV transmission line provide
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Increased line reactance
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reduced line capacitance
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reduced voltage gradient
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increased corona losses
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Answer: C
2.Values of A, B,C, D constants for the short transmission lines are respectively
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1 , Z, 0, 1
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0, 1, 1,1
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Z, 0, 1, 1
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1, 1, Z, 0
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Answer: A
3.If the receiving end voltage and the currents are numerically equal to the corresponding sending end values, then such a line is called
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infinite line
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natural line
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Tuned line
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losses line
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Answer: A
4.In which of the following model of the transmission line full charging current is assumed to flow over half the length of the line
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equivalent pi
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short line
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nominal pi
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nominal T
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Answer: D
5.Surge conductance in the power transmission lines is due the leakage over
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insulators
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conductors
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poles
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jumpers
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Answer: B
6.If the height of the tower is altered the parameter which changes is
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inductance
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capacitance
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conductance
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none
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Answer: B
7.Transmission lines are classified as short, medium and long based on
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length
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no load current
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capacitance
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both A & B
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Answer: D
8.Coefficient of reflection for current for an open ended line is
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1
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0.5
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-1
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zero
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Answer: C
9.In a transmission line, reflection coefficient is Zero, if the load resistance is ( R- surge resistance)
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0
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infinite
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1/R
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R
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Answer: D
10.Transmission lines are transposed to
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reduce copper losses
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reduce skin effect
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prevent interference with neighboring lines
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prevent short circuit between any two lines
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Answer: C
11.Inductance of a 3- phase symmetrically spaced transmission line is __________
Answer: 2 X 10-7 log d/r
12.When the regulation is positive receiving end voltage is _______ than the sending end voltage
Answer: Less
13.Capacitance and inductance per unit length of a line operating at 110 kV are 0.01
F and 2 mH, surge impedance loading of the line is ___________
Answer: 27 MVA
14.A short transmission line is the equivalent circuit consisting of ____________
Answer: Series R & series L
15.For a transmission line with R , X and negligible C , the transmission constant A is _________
Answer: R + j X
16.When the bundled conductors are used in place of single conductor the effective capacitance _____
Answer: Increases
17.A transmission line of 80 kM line is operating at 400 Hz, it can be classified as _____________ line
Answer: Long
18.Grounding is generally done in transmission line at _____ end
Answer: Middle
19.The surge impedance of 50 miles long underground cable is 50 ohms, for a 25 miles length it will be ____
Answer: 50 ohm
20.Self GMD method is used to evaluate ______________
Answer: Inductance