WAG-9 is currently the most powerful freight locomotive in Indian Railways' fleet. It is very similar to WAP-7; the only difference being the gear ratio which makes it suitable for heavy freight operations. In November 1998, CLW started producing these with indigenous components. The first one, 'NAVYUG' (translated, 'New Era'), was flagged off on Nov. 14. Like the WAP-5 units, they have GTO thyristor converters and 3-phase asynchronous motors.
Newer versions starting from WAG-9 31248 feature full IGBT traction control. The class is named as WAG-9i. There is a technical variant of this class named WAG-9H. The 'H' means Heavy. Another variant includes WAG-9Hi which seems to be a combination of the above two.
WAG-9H/9Hi are the heaviest electric locomotives and the heaviest locomotives in regular service in India. These are the only freight dedicated 3-phase AC locomotives in India. Also, WAG-9i/9Hi are the only electric locomotives in India fitted with Insulated Gate Bipolar Transistor(IGBT) as of now. They are also the freight locomotives with highest operational speed in India.
Newer versions starting from WAG-9 31248 feature full IGBT traction control. The class is named as WAG-9i. There is a technical variant of this class named WAG-9H. The 'H' means Heavy. Another variant includes WAG-9Hi which seems to be a combination of the above two.
WAG-9H/9Hi are the heaviest electric locomotives and the heaviest locomotives in regular service in India. These are the only freight dedicated 3-phase AC locomotives in India. Also, WAG-9i/9Hi are the only electric locomotives in India fitted with Insulated Gate Bipolar Transistor(IGBT) as of now. They are also the freight locomotives with highest operational speed in India.
Source :: http://en.wikipedia.org/wiki/Indian_locomotive_class_WAG-9