Railway electrification as a means of traction emerged at the end of the nineteenth century, although experiments in electric rail have been traced back to the mid-nineteenth century.

DC traction units use direct current drawn from either a conductor rail or an overhead line. Apart from a few cases, almost all AC Traction units draw alternating current from an overhead line.

Because of the variety of railway electrification systems, which can vary even within a country, trains often have to pass from one system to another. One way This is accomplished is by changing locomotives at the switching stations. These stations have overhead wires that can be switched from one voltage to another, and so the train arrives with one locomotive, and then departs with another. Often, however, This is inconvenient and time-consuming. The switching stations have very sophisticated components, and they are very expensive.

Another way is to use multi system locomotives that can operate under several different voltages and current types. In Europe, it is common to use four-system locomotives (1.5 kV DC, 3 kV DC, 15 kV 16 2/3 Hz AC, 25 kV, 50 Hz AC). These locomotives do not have to stop when passing from one electrification system to another, the changeover occurring where the train coasts for a short time.

Electro-diesel locomotives which can operate as an electric locomotive on electrified lines but have an onboard diesel engine for non-electrified sections or sidings have been used in several countries.

Presently, we are working with Indian railways upon railway electric traction.