The power loss in the sheath or screen ($\lambda_1$) consists of losses caused by circulating currents ($\lambda_{1c}$) and eddy currents ($\lambda_{1e}$), thus $\lambda_1=\lambda_{1c}+\lambda_{1e}$.

Special cases are:

Symbol
$\lambda_{\mathrm{1}}$
Unit
-
Formulae
$\lambda_{\mathrm{1c}} + \lambda_{\mathrm{1e}}$default
$\lambda_{\mathrm{1}} - \lambda_{\mathrm{2}}$cables with screen/sheath and non-magnetic armour
$- \lambda_{\mathrm{2}} + \frac{W_{\mathrm{sA}}}{W_{\mathrm{c}}}$single-core cables with screen/sheath and magnetic armour, bonded to sheath at both ends
$\frac{R_{\mathrm{sc}}}{R}$single-core concentric cable
$0$cable without screen or sheath
Related
$\lambda_{\mathrm{1c}}$
$\lambda_{\mathrm{1e}}$
$\lambda_{\mathrm{2}}$
$W_{\mathrm{c}}$
$W_{\mathrm{sA}}$
Used in
$I_{\mathrm{c}}$
$\lambda_{\mathrm{2}}$
$q_{\mathrm{2_{\mathrm{1}}}}$
$q_{\mathrm{2_{\mathrm{2}}}}$
$T_{\mathrm{eq}}$
$\theta_{\mathrm{ar_{\mathrm{1}}}}$
$\theta_{\mathrm{ar_{\mathrm{2}}}}$
$\theta_{\mathrm{c_{\mathrm{z}}}}$
$\theta_{\mathrm{e}}$
$W_{\mathrm{encl}}$
$W_{\mathrm{I}}$
$W_{\mathrm{s}}$