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Temperature steel pipe

The formulae to calculate the loss factor for steel pipe $\lambda_3$ use the resistance of the pipe $R_{sp}$ at its maximum operating temperature. Because the temperature of the steel pipe is a function of the current, $I_c$, an iterative method is used for the calculation.

With crossing heat sources, a temperature rise of $\Delta\theta_{0x}$ applies at the hottest point.

Symbol
$\theta_{sp}$
Unit
°C
Formulas
$\theta_{c}-T_{1} \left(W_{c}+\frac{W_{d}}{2}\right)-n_{ph} T_{2} \left(W_{c} \left(1+\lambda_{1}+\lambda_{2}\right)+W_{d}\right)$
Related
$\Delta \theta_{0x}$
Temperature rise by crossing heat sources [K]
$\lambda_{1}$
Loss factor shield (screen/sheath)
$\lambda_{2}$
Loss factor armour
$n_{ph}$
Number of phases in a cable
$T_{1}$
Thermal resistance conductor—sheath [K.m/W]
$T_{2}$
Thermal resistance armour bedding [K.m/W]
$\theta_{c}$
Temperature conductor [°C]
$W_{c}$
Conductor losses (phase) [W/m]
$W_{d}$
Dielectric losses (phase) [W/m]
Used in
$R_{sp}$
Electrical resistance steel pipe [$\Omega$/m]
$\theta_{spf}$
Mean temperature medium in the steel pipe [°C]