01․ If the diameter of the conductor is increased
Resistance R = ρl/a
Where,
ρ = Resistivity
l = Length of the conductor
a = area of the conductor
If the diameter of the conductor is increased, area will increase and resistance is decreased.
If the diameter of the conductor is increased, radius will increase and inductance is decreased.
If the diameter of the conductor is increased, radius will increase and inductance is decreased.02․ Due to proximity effect, the increase in conductor resistance is not negligible in
Proximity effect occurs due to current in mutual conductors. The effective area of current flowing path is reduced because of non uniform flux linkage between the two adjacent conductors.
Proximity effect is more in case of power cables, because the distance between the conductors is small. This effect is negligible in case of over head transmission lines, because the distance between the conductors is larger.
03․ The fact that current density is higher at the surface when compared to centre is known as
Accumulation of current on the surface of the conductor is called skin effect. Due to skin effect the area of current flowing path is reduced.
04․ The presence of earth in case of overhead lines
Effect of earth on transmission line capacitance:
Where,
ε = Permittivity
d = Distance between the conductor
h = Height of the tower
Therefore, Capacitance C ∝ 1/h
Capacitance is inversely proportional to height of the tower.
The effect of earth will increases the value of capacitance.
Where,
ε = Permittivity
d = Distance between the conductor
h = Height of the tower
Therefore, Capacitance C ∝ 1/h
Capacitance is inversely proportional to height of the tower.
The effect of earth will increases the value of capacitance.05․ The term self GMD is used to calculate
The inductance of single phase two wire line is
Where,
GMD = Mutual Geometric Mean Distance
GMR = Self GMD or Geometric Mean radius
Therefore, the term self GMD is used to calculate inductance of the transmission line.
Where,
GMD = Mutual Geometric Mean Distance
GMR = Self GMD or Geometric Mean radius
Therefore, the term self GMD is used to calculate inductance of the transmission line.06․ Inductance of transmission line will decrease when
Inductance of two wire transmission line
Where,
GMD = Mutual Geometric Mean Distance
GMR = Self GMD or Geometric Mean radius
Therefore, by increasing of GMR and decreasing of GMD, inductance of transmission line will decrease.
Where,
GMD = Mutual Geometric Mean Distance
GMR = Self GMD or Geometric Mean radius
Therefore, by increasing of GMR and decreasing of GMD, inductance of transmission line will decrease.
07․ If we increase the spacing between the phase conductors, the line capacitance
Capacitance of a two wire transmission line is
Where,
d = Space between the conductors
r = radius of the conductors
Therefore, if we increase the spacing between the phase conductors, the line capacitance will decrease.
Where,
d = Space between the conductors
r = radius of the conductors
Therefore, if we increase the spacing between the phase conductors, the line capacitance will decrease.08․ If we increase the length of the transmission line, the charging current
Where,
c = capacitance
f = frequency
l = length of the transmission line
Therefore, by increasing the length of transmission line, capacitive reactance will decrease and charging current increases.
09․ In triangular configuration, inductance and capacitance values are ------ and ------ respectively
Inductance of a transmission line
In triangular configuration distance between the conductors is smaller than horizontal configuration. Therefore, Inductance is less.
Capacitance of a transmission line:
In triangular configuration distance between the conductors is smaller than horizontal configuration. Therefore, capacitance is higher.
In triangular configuration distance between the conductors is smaller than horizontal configuration. Therefore, Inductance is less.
Capacitance of a transmission line:
In triangular configuration distance between the conductors is smaller than horizontal configuration. Therefore, capacitance is higher.
10․ If we increase the spacing between the phase conductors, the value of line inductance
Inductance of a transmission line
Therefore, if we increase the spacing between the phase conductors, the value of line inductance will increase.
Therefore, if we increase the spacing between the phase conductors, the value of line inductance will increase. <<<7891011>>>
