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Electric Locomotive

By on November 23, 2013

Steam Locomotive has always been a subject of curiosity amongst generation from the time introduced over Indian Railways. Railways have mainly been identified by its rhythm sound most popularly called Chuk-Chuk Jude. With the advancement of technologies led to the introduction of electric and diesel locomotive replacing steam locomotive which has now gone into oblivion. Steam locomotive now only runs historical or tourist trains to showcase the history of Railways. Source of motive power in a steam locomotive is coal, fuel energy of which is used to generate steam at high pressure. The high pressure steam works a piston providing traction to the wheel through crank connection.  With the advent of electricity and electrical motor, and many advantages associated with electric and diesel traction, it replaced the steam traction. For Electric traction, basic fuel is still coal only, but efficient use in large power houses, electricity driving traction motor with better maneuverability of speed and traction control favored the change.

diesel locomotive
WAP7 Locomotive

What an Electric Locomotive consists of

There are three types of locomotive operating over Indian Railways with different power conversion configuration.

  1. Single phase transformer with Tap changer of 32 notches at primary side and two secondary winding to feed two circuits of three traction motors connected in parallel, using bridge rectifier to convert AC into DC. (WAM4, WAG5, WAG7)
  2. Single Phase transformer with two secondary feeding to Thyristor base controlled rectifier converting AC` into controllable DC (WAG6A, B&C)
  3. Single phase transformer with step down output fed to line side and load side converter using three phase traction motor. Converter-Inverter sets converts AC into DC link Voltage and used for traction purpose either directly and after converting into three phases.

The operation of electric locomotive involves the current collection by a pantograph continuously touching the overhead wire, running over the bus-bar on the locomotive roof to surge arrester and Vacuum circuit breaker. Output of vacuum circuit breaker is connected to the transformer through condenser bushing or cable head termination.  The output of the transformer is fed to power converter and controller as shown in the diagram for different class of locomotive.  The output of the power converter and controller which is either controlled DC or three phase AC with variable voltage and variable frequency is fed to the suitable traction motor.  Traction Motor drives the wheel through reduction gears. The locomotive is supported on the wheel through bogie/bolster and suspension system. The Locomotive is a collection  of technologies prevailing and developed exclusively for the purpose or modified to the existing one. There is hardly any field of engineering not finding its role in the design and development of Electric Locomotive. Therefore, knowledge of Electric Locomotive provides an opportunity to know the adaptability and application of different technologies for a purpose.  How a locomotive works and what is there in store for you is made available in subsequent chapters.

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