# A single-phase line consists of two long solid conductors, each having a radius of r metre separated by a distance of D metre. What will be capacitance between the conductors?

A single-phase line consists of two long solid conductors, each having a radius of r metre separated by a distance of D metre. What will be capacitance between the conductors?

### Right Answer is: 0.0121/[ log (D/r)]  µF/km

#### SOLUTION

The capacitance between the conductors of a 1-ϕ, 2- long solid conductors transmission line is

= π ϵr ϵ∘ / ln(D / r)

where

D = distance of separation between two long solid conductors

r = radius of each long solid conductor

Calculations:

ϵ∘ = 8.85 × 10-12

ϵr  = 1 (for air)

π = 3.14

ln (D / r) = 2.303 log (D / r)

From equation ( i )

CAB = (3.14 × 8.85 × 10-12 × 1) / (2.303 log (D / r))

CAB = 0.0121/[ log (D/r)]  µF/km

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