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Thermal capacitance of conductor (IEC 60853)

The capacitance of the equivalent conductor for multi-core cables is equal to the sum of the capacitances of the conductors plus the capacitance of that portion of the insulation which is enclosed within the perimeter of the equivalent conductor.

Symbol
$Q_{ct}$
Unit
J/(m.K)
Formulae
$\frac{\sigma_c A_c}{{10}^6}$Single-core cables
$\frac{n_c \sigma_c A_c}{{10}^6}+\frac{\sigma_i \left({d_{ct}}^2-n_c {d_c}^2\right)}{{10}^6}$Multi-core cables, round conductors
$\frac{n_c \sigma_c A_c}{{10}^6}+\frac{\sigma_i n_c d_c t_{2i}}{{10}^6}$Multi-core cables, sector-shaped conductors
Related
$A_c$
Cross-sectional area of conductor [mm$^2$]
$d_c$
External diameter of conductor [mm]
$d_{ct}$
External diameter of conductor for transient calculations [mm]
$n_c$
Number of conductors in object
$\sigma_c$
Volumetric heat capacity of conductor material [J/(K.m$^3$)]
$\sigma_i$
Volumetric heat capacity of insulation material [J/(K.m$^3$)]
$t_{2i}$
Thickness of insulation between conductors [mm]
Used in
$Q_A$
Element A of two-part thermal circuit [J/(m.K)]
$Q_{tot}$
Total thermal capacitance, transient [J/(m.K)]