Traction motors are machines for pulling electrical energy into mechanical work. When braking, the electric switches in the generator operation converting mechanical energy into electrical energy and serve as a brake. For electric vehicles for public transport are most often used traction motors for DC (direct current) and three-phase asynchronous traction motors. Electric traction vehicles that are powered by the contact network via pantograph differ, among other things, the size and type of supply voltage. Worldwide, there are more systems electrification contact network. Electric traction vehicles basically differ in the type of applied traction electric motors and speed control mode driving. Use of the main generator and traction motors of alternating current in diesel-electric locomotives are enable by the static converters based semiconductor devices, primarily silicon diodes and thyristors. Electric locomotive is a type of traction rolling stock. This type of locomotive for drive uses traction electric motors that are powered via the contact network through a pantograph (collector electric current). In relation to the level of noise for diesel locomotives and steam locomotives, electric locomotives is the quietest in the engine. The main and the biggest lack of electric locomotive is the need for electrification of the (construction of electricity networks and associated facilities), which requires large investments. The use of electric locomotives is payable on those lines that have a very large volume of traffic, because then you can faster return on your investment. The biggest advantage of multisystem locomotives is that it can be used for traction on the lines on which alternate different feed systems take turns. This reduces costs of reelectrification of stripes.