Current Carrying Capacity Enhancement of High Voltage Underground Cables

Power cables used in underground transmission and distribution systems have conductors with large cross sections to accommodate the high current capacity. The main factors that affect cable ampacity, such as the insulation condition, soil thermal resistivity, bonding type, and depth of laying, are examined. This paper investigated the ampacity of power cables at 66 kV and 220 kV operating voltages, as well as the impact of controlled backfill thermal resistivity on heat dissipation using the implemented MATLAB program. The calculation of cable ampacity is mainly based on IEC 60287 at various conditions and the finite element method (FEM) to study the heat dissipation from the outer surface of the cable to the surface of the ground. Based on the paper results, cable ampacity is greatly affected by the installation conditions and material properties. The increased current capacity is associated with considerable dissipation of energy due to the Joule effect in the conductors.