Page NO: 2 {ABB/wag-9 loco}
3-phase Locomotives have the following advantages compared to DC motors Loco.

- Compact Size: For the same power output, a 3-phase motor is much smaller in size compared to a DC motor.
- 🛠️ Low Manintenance: 3- phase Traction Motors don’t have carbon brushes or a commutator, the maintenance cost is lower.
- High Reiliability: Induction motors are strong and durable, making 3-phase locomotives more reliable.
- 🚀 Constant Power at High Speed: In DC series motors, the rated power reduces beyond the field weakning limit, while in 3-phase locomotives, full power is maintained up to maximum speed.
- Better Overload Capacity: 3-phase locomotives have more dependable overload handling capability.
- Efficient Regenerative Braking: Regenerative braking remains available from maximum speed down to a complete stop, improving operational efficiency.
- Improved Wheel-Rail Contact: Due to a specific drop in the force- speed curve and limitation of motor speed by synchronous speed, wheel-to-rail contact is significantly improved. This allows maximum tractive efford within the permitted axle load.
- ⚡High Power Factor: Except at very low speeds, 3-phase locomotives operate at nearly unity power factor throughout the speed range.
- 🛤️ Reduced Track Wear: The lighter traction motors result in lower ‘unsprung mass’, which reduces dynamic forces on the track. As a result, there is less rail wear and minimal need for changes in track alignment.
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