LCC design criteria in electrical plants oriented to energy saving

In this paper, a life-cycle cost (LCC) approach is proposed to design electric installations suitable to industrial and civil applications. The structure of the electric system under study is supposed radial, as in most cases, and composed by transformers and lines, while users are simply represented by means of their load diagrams. The LCC procedure allows us to evaluate the main characteristics of transformers (rated power) and lines (rated current) and it can be adapted to also choose particular loads like induction motors. The paper shows an improvement of the standard procedures to design electric lines constituted by cables also including the case of their parallel connections and the most convenient types of busbars. A similar concept is also applied to transformers taking into account their thermal behavior to establish their limit performance, starting from the supplied system load characteristics. In the case of induction motors, the mechanical load is considered in the evaluation of the most convenient solution. The procedure has been applied to the case of a real industrial plant and the results reported in the paper are related to it.