Temperature factor for the accurate calculation of LV cables

Abstract

In the present article the voltage drop in a low voltage isolated cable is analyzed by the authors. This analysis considers the effect of resistivity variation with the temperature; which, as well, depends on the current. It makes to them to define the ‘temperature factor’. The authors demonstrate that the voltage drop due to the cable reactance cannot be neglected when temperature effects are taken into account. Finally, it is shown two fast, simple and systematic methods to calculate the cross-section of a LV isolated cable. These methods consider the cable real temperature and reactance. One of them is analytical and the other uses the tables of per unit voltage drop provided by manufacturers and standards.