Cableizer ®

Coefficient K in air

Symbol
$K_A$
Formulas
$\frac{\pi D_o h_{bs}}{1+\lambda_1+\lambda_2+\lambda_3} T_{int}$cables
$\frac{\pi D_o h_{bs}}{1+\lambda_1} T_{int}$PAC/GIL
$\pi D_o h_{bs} T_{hs}$heat sources
$\pi D_o h_{bs} T_{fo}$FOC
Related
$D_o$
Outer diameter [m]
$h_{bs}$
Heat dissipation coefficient for black surfaces in free air [W/m$^2$/K$^{5/4}$]
$\lambda_1$
Loss factor shield (screen/sheath)
$\lambda_2$
Loss factor armour
$\lambda_3$
Loss factor steel pipe pipe-type cable
$\pi$
Archimedes' constant $\pi$
$T_{fo}$
Thermal resistance FOC [K.m/W]
$T_{hs}$
Thermal resistance heat source [K.m/W]
$T_{int}$
Internal thermal resistance for current losses [K.m/W]
Used in
$\Delta \theta_s$
Temperature difference surface—ambient [K]