Contents I. Introduction
Rectifier systems in tramway traction substations undergo varying loads [7], [11], [16]. The studies carried out by the authors [3]–[6] have confirmed this hypothesis. It has also been found out that DC power supply system of the electric traction has some power redundancy resulting from the required overrating e.g. parameters of rectifier systems forming the basic equipment of the substations in question. Further studies and analyses of traction load details should help to develop some load description tools useful to better engineering calculations [17]. Development of engineering tools to describe better possible traction loads and of improved power supply units is a comprehensive task. One of the aspects of key importance for this matter is presented below.
