Q$6.$ A $220kV,50Hz,3-$phase, transmission line connects two substation $150$ km apart. Each phase is composed of two solid conductors which a radius $r=12\mathrm{.}5mm$ and a spacing $d=45cm.$ Phase conductors are arranged as shown in the following figure.

$(8$ marks$)$

V

Find the following:

a$.$ GMR

$(2$ marks$)$

b$.$ GMD

$(2$ marks$)$

c$.$ Capacitance between the transmission line in $\frac{F}{k}m$

Y$(2$ marks$)$

d$.$ Capacitive reactance in ohms

$(2$ marks$)$