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