Cableizer ®

Thermal resistance B transient 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
Formulas
$q_{2} T_{2}+q_{3} \left(T_{3}+T_{4i}\right)+q_{4} T_{4ii}$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 armour bedding
$q_{3}$
Ratio of losses jacket
$q_{4}$
Ratio of losses environment
$T_{1}$
Thermal resistance conductor—sheath [K.m/W]
$T_{2}$
Thermal resistance armour bedding [K.m/W]
$T_{3}$
Thermal resistance jacket [K.m/W]
$T_{4i}$
Thermal resistance medium in the duct [K.m/W]
$T_{4ii}$
Thermal resistance duct wall [K.m/W]
$T_{A}$
Thermal resistance A transient thermal circuit [K.m/W]
$T_{C}$
Thermal resistance C transient thermal circuit [K.m/W]
Used in
$\alpha_{t}$
Conductor to surface attainment factor
$M_{0}$
Coefficient M partial transient temperature rise [s]
$N_{0}$
Coefficient N partial transient temperature rise [s$^2$]
$Q_{B,ab}$
Thermal capacitance B transient thermal circuit, armour bedding [J/(m.K)]
$Q_{B,d}$
Thermal capacitance B transient thermal circuit, duct [J/(m.K)]
$Q_{B,f}$
Thermal capacitance B transient thermal circuit, filler [J/(m.K)]
$Q_{B,i}$
Thermal capacitance B transient thermal circuit, insulation [J/(m.K)]
$Q_{B,j}$
Thermal capacitance B transient thermal circuit, jacket [J/(m.K)]
$Q_{B,s}$
Thermal capacitance B transient 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]