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Apparent thermal resistance a

This is the apparent thermal resistance $T_{a0}$ used to calculate cable partial transient temperature rise acc. to IEC 60853-2.

Symbol
$T_{a0}$
Unit
K.m/W
Formulae
$\frac{1}{a_0-b_0} \left(\frac{1}{Q_A}-b_0 \left(T_A+T_B\right)\right)$
Related
$a_0$
Coefficient a for partial transient temperature rise [1/s]
$b_0$
Coefficient b for partial transient temperature rise [1/s]
$Q_A$
Element A of two-part thermal circuit [J/(m.K)]
$T_A$
Element A of equivalent thermal circuit [K.m/W]
$T_B$
Element B of equivalent thermal circuit [K.m/W]
Used in
$\alpha_t$
Conductor to surface attainment factor
$\Delta \theta_{c,t,o}$
Transient temperature rise of conductor by ohmic losses [K]
$T_{b0}$
Apparent thermal resistance b [K.m/W]