# 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 ϵ _{r} 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}

ϵ_{r} = 1 (for air)

π = 3.14

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

From equation ( i )

C_{AB} = (3.14 × 8.85 × 10-12 × 1) / (2.303 log (D / r))

**C _{AB} = 0.0121/[ log (D/r)] µF/km**