scope:

IEC&nbsp;60287-2-3:2017 describes a method for calculating the continuous current rating factor for cables of all voltages installed in ventilated tunnels. The method is applicable to any type of cable.<br /> The method applies to natural as well as forced ventilation.<br /> Longitudinal heat transfer within the cables and the surroundings of the tunnel is assumed to be negligible.<br /> All cables are assumed to be identical within the tunnel and it is assumed that the tunnel cross-section does not change with distance along the tunnel.