Question

A 5kV, 50Hz, single core lead sheath cable has core diameter of 2cm and overall diameter of 4 cm and 5 km length. If the insulation resistance of cable is $40m\Omega$, the receptivity $\rho$ of insulation is ________ $\times {10}^{12}\Omega -m$ (in two decimal places)

• A. 1.81

Answer 1

The correct option is A 1.81
$R_{ins}=\frac{{\rho }_{ins}}{2\pi \ell }\ell n\frac{R}{r}$

${\rho }_{ins}=\frac{40\times {10}^6\times 2\times \pi \times 5\times 1000}{\ell n\frac{2}{1}}\Rightarrow {\rho }_{ins}=1.81\times {10}^{12}\Omega -m$