Power Systems  II Mid  I, September  2014
1.Bundle conductors in the EHV transmission line provide

Increased line reactance

reduced line capacitance

reduced voltage gradient

increased corona losses

Answer: C
2.Values of A, B,C, D constants for the short transmission lines are respectively

1 , Z, 0, 1

0, 1, 1,1

Z, 0, 1, 1

1, 1, Z, 0

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

infinite line

natural line

Tuned line

losses line

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

equivalent pi

short line

nominal pi

nominal T

Answer: D
5.Surge conductance in the power transmission lines is due the leakage over

insulators

conductors

poles

jumpers

Answer: B
6.If the height of the tower is altered the parameter which changes is

inductance

capacitance

conductance

none

Answer: B
7.Transmission lines are classified as short, medium and long based on

length

no load current

capacitance

both A & B

Answer: D
8.Coefficient of reflection for current for an open ended line is

1

0.5

1

zero

Answer: C
9.In a transmission line, reflection coefficient is Zero, if the load resistance is ( R surge resistance)

0

infinite

1/R

R

Answer: D
10.Transmission lines are transposed to

reduce copper losses

reduce skin effect

prevent interference with neighboring lines

prevent short circuit between any two lines

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