Equivalent thermal resistance of the soil per unit surface

The Equivalent thermal resistance of the soil per unit surface, representing convection, is equal to a value of 0.20 K.m$^2$/W.Refer to CIGRE Guide 218 or Electra 125 'Calculation of the continuous rating of three core, rigid type, compressed gas insulated cables in still air and buried'.

Symbol
$\beta_{T}$
Unit
W/(K.m$^2$)
Used in
$d_{im}$