Cableizer ®

Max permissible conductor temperature rise in the steady-state

Conductor temperature rise above ambient of $I_R$ in the steady state, i.e. the standard maximum permissible temperature rise.

Using the IEC equation for emergency rating results in a small deviation to the result from CIGRE TB 880 case study 11 which leads to $h_{2R} > 1$. Also note that a higher value for $I_{c_{2}}$ results when calculated with per-phase values of $R_{c_{1}}$, $R_{c_{R}}$, $R_{c_{2}}$, $\delta\theta_{R_{t}}$, and $\delta\theta_{R_{\infty}}$.

Symbol
$\delta \theta_{R,\infty}$
Unit
°C
Formulas
$\theta_{cmax}-\theta_a-\Delta \theta_{d,t}$Cableizer
$\delta \theta_{c,\infty}-\Delta \theta_{d,t}$IEC 60853-2 emergency rating
$\theta_c-\theta_a-\Delta \theta_{d,t}$IEC 60853-2 cyclic rating
Related
$\delta \theta_{c,\infty}$
Steady-state temperature rise conductor [K]
$\Delta \theta_{d,t}$
Transient temperature rise by dielectric losses [K]
$\delta \theta_R$
Conductor temperature rise above ambient temperature [K]
$\theta_a$
Ambient temperature [°C]
$\theta_c$
Temperature conductor [°C]
$\theta_{cmax}$
Max. temperature conductor [°C]
Used in
$I_{c,2}$
Emergency overload current [A]
$r_{2R}$
Operating point ratio [-]