Computer Program Analysis Heat Flow from Cables Buried in Regions of Discontinuous Thermal Resistivity

The ampacity, or current-carrying capacity, of a buried power cable is determined to a large degree by the effective thermal resistance of the earth to the heat flowing from the cable to the ambient earth surface. Often the heat passes through sharp discontinuities in the earth, where the thermal resistivity changes. Analysis of the thermal circuit in such cases can be performed easily by means of the computer program presented in this paper. Calculations are based on a resistive network model of the thermal path between cable and ambient earth surface.