Question

A $\mathbf{60}\mathbf{}\mathit{H}\mathit{z}\mathbf{}\mathbf{,}\mathbf{}\mathbf{765}\mathbf{}\mathit{k}\mathit{V}\mathbf{}\mathbf{,}$three-phase overhead transmission line has four ACSR $\mathbf{900}\mathbf{}\mathit{k}\mathit{c}\mathit{m}\mathit{i}\mathit{l}$54/3 conductors per phase. Determine the $\mathbf{60}\mathbf{}\mathit{H}\mathit{z}$resistance of this line in ohms per kilometer per phase at $\mathbf{50}\mathbf{°}\mathbf{}\mathit{C}$.

Short answer

Answer

Therefore, the resistance of each conductor is $0.01841\frac{\Omega }{km}$.

Step-by-step solution

Given data.

There are four ACSR conductors.

The supply frequency is 60 Hz.

The supply voltage is 765 kV.

The temperature is $50°C$.

Determine the formula of resistance.

Write the formula of resistance per conductor.

${\mathit{R}}_{\mathbf{60}\mathbf{}\mathbf{H}\mathbf{z}\mathbf{,}\mathbf{50}}\mathbf{=}\frac{\mathbf{R}}{\mathbf{4}}$ ……. (1)

Here, R is the total resistance.

Determine the resistance.

From table A-4, the resistance of ACSR conductors for $50°C$is,

$R=0.1185\frac{\Omega }{mil}$

Convert mile into kilometers by multiplying mil with 1.609 km.

$$\begin{gathered} R=0.1185\frac{\Omega }{1.609}km \\ =0.07365\frac{\Omega }{km} \end{gathered}$$

Substitute $0.07365\frac{\Omega }{km}$for R in equation (1).

$$\begin{gathered} R_{50Hz,50}=\frac{0.07365{\displaystyle \frac{\Omega }{km}}}{4} \\ =0.01841\frac{\Omega }{km} \end{gathered}$$

Therefore, the resistance of each conductor is $0.01841\frac{\Omega }{km}$.