This is the new load current applied as a step function to a system with given operating conditions.

For the emergency rating it is the sustained (100% load factor) rated current for the conductor to attain, but not exceed, the standard maximum permissible conductor temperature θcmax.

Symbol
$I_{\mathrm{R}}$
Unit
A
Related
$\theta_{\mathrm{cmax}}$
Used in
$h_{\mathrm{1}}$
$I_{\mathrm{2}}$