An Equivalent Circuit for the Thermal Analysis of Power Cables Installed in Solid Bottom Trays

This thesis proposes a methodological approach for the thermal rating of power cables installed in solid bottom trays with and without covers. The National Electric Code (NEC) gives an equation to compute the ampacity of cables in ventilated trays. However, for solid bottom trays, it provides no information on how to compute the effective thermal resistance between the conductors and the surroundings. In this paper an analog thermal-electrical circuit is derived from first thermodynamic principles. The circuit parameters are easy to compute. The method is completely general and can be applied to cables of any size and voltage level. A hand-worked example is given for illustration. The validity of the model is corroborated through numerous FEM simulations and laboratory experiments.