The calculation of cable parameters using combined thermal and electrical circuit models

A methodology that can be used to calculate underground power cable ampacities and other cable parameters is presented. Capabilities of the methodology include the ability to model (both thermally and electrically) conductors, shields, and neutrals in an underground cable system. Currents are calculated from the electrical circuit model and are used in the thermal analysis of the cable system. Temperature-dependent parameters are determined on the basis of calculated system temperatures. Solutions of both the thermal and electrical circuit models are performed with an iterative procedure until convergence based on conductor temperature occurs. Results from this procedure include not only the calculation of thermal parameters, such as cable ampacities and system temperatures, but also electrical parameters, such as cable voltage drops and open-circuited shield voltages