Transformers in electric trains?

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SUMMARY

The discussion centers on the economic advantages of using transformers in electric trains compared to running overhead lines at 400V. Phil N explains that overhead lines transmit electrical current over long distances, where increasing voltage reduces current, thereby minimizing power losses due to resistance (I²R losses) and reactance. Transformers are essential for stepping down high voltage to levels suitable for train motors, enhancing efficiency and reducing operational costs.

PREREQUISITES
  • Understanding of electrical power principles, specifically Power = Current * Voltage
  • Knowledge of resistive and reactive power losses in electrical systems
  • Familiarity with transformer functionality and applications in electrical engineering
  • Basic concepts of high voltage transmission systems
NEXT STEPS
  • Research the principles of electrical power transmission and losses in AC systems
  • Study the design and operation of transformers in electrical applications
  • Explore the economic impacts of high voltage transmission versus low voltage systems
  • Investigate the role of transformers in other transportation systems, such as trams and subways
USEFUL FOR

Electrical engineers, transportation system designers, and students studying electrical power systems will benefit from this discussion, particularly those focusing on the efficiency and economics of electric train operations.

cabellos
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I have an exam on monday and looking through the past papers I came across a question I couldn't find a suitable answer to:

List the economical advantages of using a transformer in a train rather than run the overhead lines at 400V?

any help would be very much appreciated...

Phil N
 
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Well very simply, overhead lines carry electrical current long distances and since Power = Current * Voltage (for AC it's an integral of I(t)*V(t), but essentially the same principle), the current is reduced as voltage increases.

So to minimize power resistive (I2R) and reactive losses, high voltage is used. In the transformer the high voltage is reduced (dropped down) to a voltage suitable for a motor.
 

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