Overhead railway electrification takes place where electrical energy to the locomotives is supplied where the process can occur concurrently without the aid of board movers. Numerous systems are used all over the world. Normally there is immense benefit of using these systems but you need immense funds for their implementation. One of the main benefits is higher power to weight ratio as compared to diesel and steam engines. There is a dearth of exhaust fumes, less smoke and less needs for power as far as maintenance and power purposes are concerned. As compared to the diesel engines they are known to emit less smoke. In fact the system is highly efficient as there is no need to shift as far as traction is concerned. This system works in a similar way as far as the concept of flash welding is concerned.
The suburban regions do provide definite benefits because of being highly electrified. Suppose there is a wiring breakdown, these trains do come to a standstill. They are classified on the basis of 3 types which are voltage, current and contact systems. Various kinds of voltage systems are used by nations all around the world. As far as the early electric systems are concerned they relied on low voltage DC to connect the motors whereby a combination of resistors is used. The low voltages are used in the case of third and fourth railways. In the mid part of the 20th century the rotary convertors came into prominence. Now the process is undertaken by semi -conductors that help to rectify the process where the voltage from the utility supply is cut off. The process of DC is quite simple as DC systems are used in the process.
One more option termed as third rail ceases to be a great option for usage up to 1200 V. The reason on why it is put to use is that it carries more than 41 % of the AC system that is at the same level as compared to the level of voltages. This is a compact system and is used in the case of small tunnels. Normally they are designed for the top, side and contract systems. In fact the option is really safe when you compare it to the others as the side along with bottom contracts have a safe standard in terms of shield that are carried over by the rails. By the use of this system it limits the size along with the speed of the trains. It is a vital factor that helps to save the overhead along with voltage for the urban usages. These trains even go on to use the third train current location. On similar lines like a flash butt wielding rail you need to exercise a sense of caution.
As far as the alternating current is concerned, you can transform it into high voltages within the locomotives. This paves way for small currents or high voltages to exist within the locomotives. Once you change the taps the voltage changes power.