Cables in unfilled ducts – comparison between IEC 60287 and FEM

Installation of cables in unfilled plastic ducts is a commonly used installation method both for land cables in trench and Horizontal Directional Drilling (HDD), as well as offshore cables at landfall. The standard for cable rating calculations, IEC 60287-2-1 [1], provides a method for calculation of unfilled ducts. The method is limited to cables with diameters between 25 mm and 100 mm, or between 75 mm to 125 mm for equivalent diameter of three cables in same duct. The paper presents Finite Element Method (FEM) simulations of different cable and duct sizes in different installations and compares with results from IEC method. The method for unfilled ducts in IEC 60287-2-1 is shown to give matching or conservative results also for cable diameters outside of its defined range for all…