This factor $h_1$ is used to calculate $I_2$.

It is the factor between the constant current applied to the cable prior to the emergency loading $I_1$ ($=I_c$) to the sustained (100% load factor) for rated current $I_R$ for the conductor to attain, but not exceed, the standard maximum permissible temperature.

Symbol
$h_{\mathrm{1}}$
Unit
-
Formulae
$\frac{I_{\mathrm{1}}}{I_{\mathrm{R}}}$
Related
$I_{\mathrm{1}}$
$I_{\mathrm{R}}$
Used in
$I_{\mathrm{2}}$