- Category
- Electric Locomotive & Energy Technology
- Used for
- Efficient propulsion and braking of modern electric locomotives and trainsets
- Benefits
- Higher traction efficiency, precise motor control, improved acceleration, reduced brake wear and recovery of electrical energy during braking.
- Introduced
- 1993 — three-phase AC locomotives procured; manufacturing in India began from 1995
Three-phase electric traction represented a major advancement in Indian Railways locomotive technology. Indian Railways procured three-phase AC electric locomotive technology from ABB in the early 1990s, with manufacturing subsequently beginning at Chittaranjan Locomotive Works.
Modern three-phase locomotives use sophisticated electronic converters to control the voltage and frequency supplied to AC traction motors. This allows precise control over locomotive power, speed and tractive effort.
A major advantage is regenerative braking. During braking, traction motors can operate as generators. Instead of converting all of the train's kinetic energy into heat through friction braking, part of the recovered electrical energy can be returned to the overhead electrical network.
Three-phase propulsion technology has been used across locomotive families such as WAP-5, WAP-7 and WAG-9 and has also influenced newer EMUs, MEMUs and electric trainsets.
Indian Railways has progressively adopted newer IGBT-based traction converters, further improving control, reliability and energy efficiency.