T $T0_{gas}$Gas reference temperatureK
$T_1$Thermal resistance between one conductor and sheathK.m/W
$t_1$Thickness of insulation to sheathmm
$t_{1t}$Thickness of insulation to sheath, transientmm
$T_2$Thermal resistance of armour beddingK.m/W
$t_2$Thickness of bedding under armourmm
$t_{2i}$Thickness of insulation between conductorsmm
$T_3$Thermal resistance of jacketK.m/W
$t_3$Thickness of serving over armourmm
$T_{4d}$Transient thermal resistance for daily loadK.m/W
$T_{4db}$Correction of thermal resistance for backfillK.m/W
$T_{4i}$Thermal resistance of medium in the ductK.m/W
$T_{4ii}$Thermal resistance of the duct wallK.m/W
$T_{4iii}$Thermal resistance to ambientK.m/W
$T_{4mu}$Thermal resistance to ambientK.m/W
$T_{4ss}$Steady-state thermal resistanceK.m/W
$T_{4t}$Equivalent thermal resistance for tunnelK.m/W
$T_{4w}$Transient thermal resistance for weekly loadK.m/W
$T_{4y}$Transient thermal resistance for yearly loadK.m/W
$T_A$Element A of equivalent thermal circuitK.m/W
$T_a$Star thermal resistance of airK.m/W
$T_{a0}$Apparent thermal resistance aK.m/W
$t_{a,1}$Thickness of 1st armourmm
$t_{a,2}$Thickness of 2nd armourmm
$t_{ab}$Thickness of armour beddingmm
$T_{ab}$Thermal resistance of armour beddingK.m/W
$t_{ab,1}$Thickness of 1st armour beddingmm
$t_{ab,2}$Thickness of 2nd armour beddingmm
$T_{air}$Absolute air temperatureK
$t_{ar}$Thickness of armourmm
$T_{at}$Thermal resistance by convection, air to tunnelK.m/W
$T_{axial}$Axial thermal resistance due to the movement of air through the tunnelK.m/W
$T_B$Element B of equivalent thermal circuitK.m/W
$T_{b0}$Apparent thermal resistance bK.m/W
$T_{bulk}$Bulk temperatureK
$t_c$Thickness of hollow conductormm
$T_C$Element C of equivalent thermal circuitK.m/W
$t_{comp}$Thickness of compartmentmm
$T_{conv,ce}$Thermal resistance by convection, conductor to enclosureK.m/W
$T_{conv,od}$Thermal resistance by convection, object to ductK.m/W
$T_{conv,sa}$Thermal resistance by convection, surface to airK.m/W
$t_{corr}$Thickness of corrugation fillingmm
$t_{cs}$Thickness of conductor shieldmm
$t_{ct}$Thickness of conductor tapemm
$T_d$Internal thermal resistance for dielectric lossesK.m/W
$t_d$Thickness of ductmm
$T_e$External thermal resistance of tunnelK.m/W
$t_{EMF}$Time step to calculate current sources
$t_{encl}$Thickness of enclosuremm
$T_{eq}$Equivalent thermal resistanceK.m/W
$t_f$Thickness of filler/belt insulationmm
$T_{gas}$Absolute gas temperatureK
$T_i$Thermal resistance of insulationK.m/W
$t_i$Thickness of insulationmm
$t_{icore}$Thickness of core insulationmm
$t_{ins}$Thickness of insulationmm
$T_{ins}$Thermal resistance of insulationK.m/W
$T_{int}$Internal thermal resistance for current lossesK.m/W
$t_{is}$Thickness of insulation screenmm
$T_{is}$Thermal resistance of insulation screenK.m/W
$t_j$Thickness of jacketmm
$T_j$Thermal resistance of jacketK.m/W
$t_{jj}$Thickness of additional layer over jacketmm
$t_k$Duration of short-circuits
$T_L$Thermal longitudinal resistanceK.m/W
$T_{mh}$Mutual thermal resistance between rated and crossing objectK.m/W
$T_{mh,v}$Mutual thermal resistance per sliceK.m/W
$T_o$Thermal resistance of the oil in the pipeK.m/W
$t_{prot}$Thickness of protective covermm
$T_{prot}$Thermal resistance of protective coverK.m/W
$T_r$Total thermal resistanceK.m/W
$T_{rad,ce}$Radiation thermal resistance, conductor to enclosureK.m/W
$T_{rad,od}$Radiation thermal resistance, object to ductK.m/W
$T_{rad,sa}$Radiation thermal resistance, surface to airK.m/W
$T_{rad,sun}$Solar radiation thermal resistanceK.m/W
$T_{riser}$Thermal resistance of riser/J-tubes in air/waterK.m/W
$T_s$Star thermal resistance of objectK.m/W
$T_{sa}$Thermal resistance by convection, surface to airK.m/W
$t_{sc}$Thickness of the screenmm
$t_{scb}$Thickness of screen beddingmm
$T_{scb}$Thermal resistance of screen beddingK.m/W
$t_{scs}$Thickness of screen servingmm
$T_{scs}$Thermal resistance of screen beddingK.m/W
$t_{sh}$Thickness of the sheathmm
$t_{sha}$Total thickness between separate sheath and armourmm
$t_{shj}$Thickness of sheath jacketmm
$T_{shj}$Thermal resistance of sheath jacketK.m/W
$t_{skid}$Thickness of skid wiresmm
$t_{sp}$Thickness of steel pipemm
$T_{st}$Radiation thermal resistance, surface to tunnelK.m/W
$T_{surf}$Absolute surface temperatureK
$t_t$Wall thicknessm
$T_t$Star thermal resistance of tunnelK.m/W
$T_{tot}$Total thermal resistance, transientK.m/W
$T_{tr}$Thermal resistance of troughK.m/W
$T_{tw}$Thermal resistance of tunnel wallK.m/W
$T_{wall}$Thermal resistance of pipe wallK.m/W
$\mathrm{tan} \delta_i$Loss factor of insulation
$\tau$Transient load periods
$\tau_{ar}$Armour anglerad
$\tau_L$Transient load period for deep burials
$\theta_{2K}$Temperature rise for 2K criterion°C
$\theta_a$Ambient temperature°C
$\theta_{abs}$Absolute temperatureK
$\theta_{air}$Ambient air temperature°C
$\theta_{ar}$Temperature of armour°C
$\theta_{at}$Air temperature with load°C
$\theta_{at,0}$Air temperature with no load°C
$\theta_{at,i}$Air temperature of previous iteration cycle°C
$\theta_{at,L}$Air temperature in tunnel at outlet°C
$\theta_{at,z}$Air temperature in tunnel at z°C
$\theta_c$Temperature of conductor°C
$\theta_{c,z}$Conductor temperature at z°C
$\theta_{cmax}$Max. conductor temperature°C
$\theta_{cmaxeo}$Max. emergency overload conductor temperature°C
$\theta_{cmaxsc}$Max. short-circuit conductor temperature°C
$\theta_{de}$Temperature of duct outer wall°C
$\theta_{di}$Temperature of duct inner wall°C
$\theta_{dm}$Mean temperature of the medium in the duct°C
$\theta_e$External temperature of the object°C
$\theta_{encl}$Temperature of enclosure°C
$\theta_f$Temperature of filler for multi-core cables type SS with sheath°C
$\theta_{film}$Film temperature°C
$\theta_{gas}$Gas temperature°C
$\theta_{hs}$Temperature of heat source°C
$\theta_{kf}$Final temperature°C
$\theta_{ki}$Initial temperature°C
$\theta_{kmax}$Maximal temperature of non-insulation material°C
$\theta_{max}$Temperature of conductor at end of emergency loading°C
$\theta_o$Outer surface temperature°C
$\theta_{o,L}$Temperature of the surface of object at outlet°C
$\theta_{o,z}$Temperature of the surface of object at z°C
$\theta_{omax}$Max. outer surface temperature°C
$\theta_R$Rated current transient to steady-state ratio
$\theta_s$Temperature of screen/sheath°C
$\theta_{sc}$Temperature of screen°C
$\theta_{sh}$Temperature of sheath°C
$\theta_{sp}$Temperature of steel pipe°C
$\theta_{spf}$Mean temperature of the medium in the steel pipe°C
$\theta_{surf}$Surface temperature°C
$\theta_t$Temperature of inner tunnel wall°C
$\theta_{t,L}$Temperature of tunnel wall at outlet°C
$\theta_{t,z}$Temperature of tunnel wall at z°C
$\theta_{tm}$Mean temperature between surface and air in tunnel or trough°C
$\theta_{to}$Temperature of outer tunnel wall°C
$\theta_{to,z}$Temperature of outer tunnel wall at z°C
$\theta_w$Water temperature°C
$\theta_x$Critical soil temperature°C
$TQ$Cable thermal time constants