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Element B of equivalent thermal circuit

In the case of cables in air, the transient temperature rise of conductor above outer surface is obtained by replacing $T_B$ by $(T_B+T_C)$.

Symbol
$T_B$
Unit
K.m/W
Formulae
$q_2 T_2+q_3 \left(T_3+T_{4i}\right)+q_4 T_{4ii}$long-term transients
$\frac{T_1}{2}+q_2 T_2+q_3 \left(T_3+T_{4i}\right)+q_4 T_{4ii}$short-term transients
$T_B+T_C$cables in air
Related
$q_2$
Ratio of losses affecting armour bedding
$q_3$
Ratio of losses affecting jacket
$q_4$
Ratio of losses affecting environment
$T_1$
Thermal resistance between one conductor and sheath [K.m/W]
$T_2$
Thermal resistance of armour bedding [K.m/W]
$T_3$
Thermal resistance of jacket [K.m/W]
$T_{4i}$
Thermal resistance of medium in the duct [K.m/W]
$T_{4ii}$
Thermal resistance of the duct wall [K.m/W]
$T_A$
Element A of equivalent thermal circuit [K.m/W]
$T_C$
Element C of equivalent thermal circuit [K.m/W]
Used in
$\alpha_t$
Conductor to surface attainment factor
$M_0$
Coefficient M for partial transient temperature rise [s]
$N_0$
Coefficient N for partial transient temperature rise [s$^2$]
$Q_{B,ab}$
Element B of two-part thermal circuit of armour bedding [J/(m.K)]
$Q_{B,d}$
Element B of two-part thermal circuit, duct [J/(m.K)]
$Q_{B,f}$
Element B of two-part thermal circuit, filler [J/(m.K)]
$Q_{B,i}$
Element B of two-part thermal circuit, insulation [J/(m.K)]
$Q_{B,j}$
Element B of two-part thermal circuit, jacket [J/(m.K)]
$Q_{B,s}$
Element B of two-part thermal circuit, screen/sheath [J/(m.K)]
$T_{a0}$
Apparent thermal resistance a [K.m/W]
$T_{b0}$
Apparent thermal resistance b [K.m/W]