Q$\mathrm{.}3$: If there are $15$ insulators suspended at the string of $230$ kV overhead line, the voltage across the last three insulators near the conductor is $55$ kV $,$ and the pin$-$to$-$earth capacitance of the three last insulators start from the conductor are $0\mathrm{.}11,0\mathrm{.}13,$ and $0\mathrm{.}15$ respectively of self$-$capacitance, calculate the string efficiency? What is the capacitance across the last three insulators if the charge across each one of them is $23C$