The locomotive was developed after a previous class WAP-1 was found inadequate to haul the longer, heavier express trains (24-26 coaches) that were becoming the mainstay of the Indian Railways network. It was introduced in 1994, with a similar bodyshell to the WAP-1 class, but with Hitachi traction motors developing 5,000hp (3,700kW) (5,350hp or 3,990kW starting).
Electricals are traditional DC loco type tap changers, driving 6 traction motors arranged in Co-Co fashion. This locomotive has proved to be highly successful, with over 800 units in service. Newer examples have been fitted with Microprocessor Controlled diagnostics, Static Converter units (instead of arnos) and roof mounted Dynamic (Rheostatic) Brakes.
The locomotive can be seen in service across the electrified network of Indian Railways and is homed at 14 sheds (depots).
The last locomotive produced by the Chittaranjan Locomotive Works (CLW) was numbered 25051 in December 2015 and production of this locomotive has been stopped.