Electrical Power Systems

Capacitance of Transmission Lines 59
calculation with the exception that the radius r of each conductor is used; If d is the bundle
spacing, then for two conductor arrangement,
Ds = bg rd
1
2 ...(3.31)
or three conductor arrangement (equilateral triangle)
Ds = r. d
or a four conductor (quadruplex) arrangement,
1
2 3 e j ...(3.32)
1
3 4
Ds = e 2 . r. dj
...(3.33)
Considering the line to be transposed, the capacitance per phase is given as
HG
Can = 00242 .
eq
log D
D
s
I
KJ
m/km ...(3.34)
3.6 CAPACITANCE O THREE PHASE DOUBLE CIRCUIT LINES
igure 3.7 shows three phase double circuit line with the three sections of the transposition
cycle.
ig. 3.7: Three sections of three phase double circuit transposed line.
Each phase conductor is transposed within its groups. The effect of ground and shield wires
are considered to negligible. In this case per phase equivalent capacitance to neutral is
Where
HG
Can = 00242 .
eq
log D
D
I
KJ
m/km ...(3.35)
s
b g 1
3 ...(3.36)
D eq = D D D
ab bc ca
b g 1
D s = D D D
sa sb sc
3 ...(3.37)