A “Thermal-conductive Simplified Model” for the Actual Temperature of Overloaded Cables

Abstract

Thermal-conductive models are relatively new, and have allowed the study and thermal characterization of electrical wires in overload state. Unlike the models of resistivity, or “Joule type models”, which form the basis of energy losses in wires based only on the properties of the conductors at given temperatures, the thermal-conductive models consider the behavioral characteristics of electromagnetic energy in the form stipulated by Maxwell's equations (electromagnetic model), as well as the behavioral characteristics of energy in form of heat, stipulated by the governing equations of conduction, convection and radiation. The ambient that surrounds the wire becomes very important, as well as the shape of the electromagnetic wave that is conducted in the material. Recent work has given unexpected results in the behavior of electrical conductors under states of overload. The usual models of Joule effect, were not able to predict these effects in overload, and have been used the new thermal-conductive models, with very high levels of accuracy in the predictions of global warming. Experimentally the tests have demonstrated that in overload the heat dissipation can be more than 50% higher than what is predicted by Joule type models, and theoretically, thermal-conductive models have accuracy with less than 0.01% of total error (energy and temperature). But these thermal-conductive models currently require the use of a large amount of mechanical and electromagnetic equations, apart from a large amount of data (for ambient), which are highly variable, leading to the use of extensive modeling programs work for a long time for the characterization of a single wire in a particular state. In this paper we show a simplified thermal-conductive model, not only with sufficient precision for use in calculations of effective thermal dissipation, but also with sufficient simplicity, for use even in manually way.