Electric traction systems are used in transportation to power vehicles, such as trains, trams, trolleybuses, and some types of electric vehicles. These systems use electricity to propel the vehicles, reducing or eliminating the need for fossil fuels and contributing to cleaner and more efficient transportation. Here are the different types of electric traction systems:
Overhead Line (OHL) System: This is one of the most common electric traction systems for trains and trolleybuses. It involves an overhead wire (catenary) suspended above the track or road, which supplies electricity to the vehicle through a pantograph or trolley pole. The pantograph collects power from the overhead wire and transfers it to the vehicle's electric motors.
Third Rail System: In this system, an electric conductor, usually a metal rail or a conductor placed alongside the running rails, provides power to the train. The train collects power from the third rail using a shoe or a sliding contact attached to its undercarriage.
Battery Electric Traction: This system is used in some modern electric vehicles, especially buses and some trains. It involves using onboard batteries to store electricity, which powers the vehicle's electric motors. These batteries can be recharged through various means, such as plug-in charging stations or regenerative braking.
Hybrid Electric Traction: Some transportation systems use a combination of electric traction and other forms of propulsion. For instance, a train may be equipped with both electric motors and a diesel engine, allowing it to switch between electric power from overhead lines and using diesel power when electrified tracks are not available.
Inductive Charging System: Inductive charging is a wireless method of transferring electrical energy to a vehicle's onboard batteries. The charging process occurs without physical contact between the charging infrastructure and the vehicle. Inductive charging systems are used in some electric buses and could be applicable to other forms of electric transportation as well.
Hydrogen Fuel Cell Electric Traction: While not purely electric traction, hydrogen fuel cell vehicles can be considered under the electric traction umbrella as they use electricity generated from onboard fuel cells to power electric motors that drive the vehicle.
Each type of electric traction system has its advantages and applications based on factors like the type of transportation, infrastructure, and energy requirements. As technology advances, we may see new and innovative electric traction systems emerge in the transportation industry.