Why industrial motors etc need 3 phase power?

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SUMMARY

Industrial motors require three-phase power due to their design, which allows for a constant rotating magnetic field essential for high torque and efficiency. In contrast, high-speed trains like the TGV utilize a single-phase 25 kV AC electrification system, relying on advanced electronics and variable frequency drives to manage traction motors. These traction motors can vary their speed, unlike typical industrial motors that operate at fixed speeds. The starting configuration of industrial motors often involves a Y-Delta transition to manage current demand effectively.

PREREQUISITES
  • Understanding of three-phase power systems
  • Knowledge of variable frequency drives (VFDs)
  • Familiarity with motor starting configurations (Y-Delta)
  • Basic principles of electromagnetic induction in motors
NEXT STEPS
  • Research the operation and benefits of variable frequency drives (VFDs)
  • Explore the principles of three-phase power generation and distribution
  • Learn about the Y-Delta starting method for industrial motors
  • Investigate the design and functionality of traction motors in high-speed trains
USEFUL FOR

Electrical engineers, industrial motor designers, and professionals involved in railway electrification and motor control systems will benefit from this discussion.

Charles123
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Why industrial motors etc need 3 phase power and something like a TGV (high-speed train) only needs 1 phase (25 kV AC railway electrification), and yet its capable of such performance?
 
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I don't know much about the train, but I suspect it has a bucket-load of expensive electronics supporting it's motors. Industrial motors that hard start and go one speed are serving a different function than traction motors, which must vary their speed. In all likelihood, your train has a three phase, variable frequency drive on the traction motors.

Typical industrial motors are minimalistic. The three phases are oreiented such that a constant rotating magnetic vector spins around at some ratio of the line frequency (i.e 1:1 - 3600RPM, 1:2 - 1800 RPM, 1:4 - 900 RPM).
Typically, they'll start with some means of limiting the current demand (i.e operating in a Y configuration), and then as they speed up, they switch to a full power configuration (Delta).
 

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