Cross-sectional area of protective cover

Symbol
$A_{prot}$
Unit
m$^2$
Formulae
$\frac{\pi}{4} \left({D_{prot}}^2-{D_{encl}}^2\right)$GIL/PAC
$\frac{\pi}{4} \left({D_{prot}}^2-{D_{ins}}^2\right)$heat source