Introduction to Railway Systems

This chapter introduces the main features of a rail system that are the basis of differentiation of the various lines around the world. It discusses the types of electric power supply in railway lines. DC electrification systems are used in road‐bound urban transport systems, such as metros, streetcars, and so on, with voltages of approximately 750‐1500 V and preferable to those at alternating current for their lower impact on the medium‐voltage power supply networks. It was therefore possible to break free from the railway frequency and introduce the single‐phase electrification system at mains frequency. The use of the three‐phase alternating current has substantially been justified by the possibility of using the three‐phase asynchronous motor for traction, with its high qualities of strength and economic feasibility and its potential to be powered directly even at voltages of a few kilovolts.