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How does a diesel electric locomotive work?

“A locomotive is a type of rail transport that provides all the power to move or drive a train. It is powered by a locomotive engine. In this case, diesel, electricity, or steam power is used.

The components used in the powertrain of a locomotive diesel-electric engine are:

  • V-12/V-16/V-18 diesel engines
  • Alternator
  • Transformers
  • Rectifier
  • Inverter
  • Traction motor
  • Wheel axle

The diesel engine, which typically has a V-shaped configuration with 12, 16, or 18 cylinders, is commonly used in locomotives. However, it does not directly supply power to the axle. The engine’s flywheel rotation speed is usually more than 1000 RPM, and it is coupled with the alternator in the locomotive.

The alternator plays a crucial role. As the engine rotates, the alternator produces 770 volts and 4520 amps of current. The locomotive’s alternator has two coils:

  • Main Alternator
  • Auxiliary Alternator”

 

  1. The cooling system, lighting system, etc., of the locomotive are operated by the current obtained through the Auxiliary Alternator.
  2. The AC current generated in the main alternator is sent to the transformer.
  3. Transformer: This transformer is used to transmit the AC current from the main alternator to a specified voltage. From the transformer, this current goes to the rectifier.
  4. Rectifier: The AC current coming from the transformer is converted into DC current through this rectifier. This DC current is then sent to the inverter.
  5. Inverter: After receiving this DC current at the inverter, it converts this DC current back into AC current. As a result, a certain amount of AC current is obtained. A 3-phase AC supply is drawn from this inverter, which is connected to the traction motor.
  6. Traction Motor (AC Motor): The 3-phase AC current from the inverter drives the 6 traction motors in the locomotive. That is, there is one AC motor on each axle. These 6 traction motors are connected to the axles through gears.
  7. Wheel Axles: Six axles are connected to the total 12 wheels on the locomotive, which bear all the burden of running the train.

In summary: Diesel Engine ➡ Alternator ➡ Transformer ➡ Rectifier ➡ Inverter ➡ Traction Motor ➡ Axle

Additionally, it’s worth noting that many locomotives use DC motors, in which case there is no need for an inverter.