Question

A single phase overhead transmission line has two conductors of diameter 1 cm with a spacing of 1 meter between centres. If the dielectric strength of air is 21 kV/cm, the voltage for which corona will commence on the line is _____ kV.

• A. 55.6

Answer 1

The correct option is A 55.6
The critical disruptive voltage
$V_d=21\delta rln\left(\frac{d}{r}\right)=21\times 1\times 0.5ln\left(\frac{100}{0.5}\right)kV$
= 55.6 kV