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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
Formulas
$\frac{1}{a_{0}-b_{0}} \left(\frac{1}{Q_{A}}-b_{0} \left(T_{A}+T_{B}\right)\right)$
Related
$a_{0}$
Coefficient a partial transient temperature rise [1/s]
$b_{0}$
Coefficient b partial transient temperature rise [1/s]
$Q_{A}$
Thermal capacitance A transient thermal circuit [J/(m.K)]
$T_{A}$
Thermal resistance A transient thermal circuit [K.m/W]
$T_{B}$
Thermal resistance B transient thermal circuit [K.m/W]
Used in
$\alpha_{t}$
Conductor to surface attainment factor
$\delta \theta_{c,t,o}$
Transient temperature rise conductor by ohmic losses [K]
$T_{b0}$
Apparent thermal resistance b [K.m/W]