Problem $3(20$ Points$)$: A transmission line in a $60-Hz$ system has the conductor layout shown in Figure $1.$ Each circle in Figure $1$ represents a conductor. Each conductor is stranded with an outside diameter of $4$ cm and GMR $=1\mathrm{.}2cm.($Note: ${}_0=4{}^{**}{10}^{-7}I\frac{\text{I}}{m},{}_0={8\mathrm{.}85}^{**}{10}^{-12}\frac{F}{m})$

$f=60H2$

$D=0\mathrm{.}04m$

$D_s=0\mathrm{.}012m$

${}_0=8\mathrm{.}85{10}^{-12}\frac{F}{m}$

rigure $1$

$*a$

$\{\begin{array}{c}\text{:}{x}_c=267540\mathrm{.}98\\ km\end{array}$

$2-$Bundle: