The model name stands for broad gauge (W), AC Current (A), Goods traffic (G), 9th generation (9) locomotive.

A passenger variant of the WAG-9 was developed, the WAP-7, with a modified gear ratio to pull lighter loads at higher speeds.

Newer WAG-9 units have "CLW Glorious 60 years" marked on their sides.

[3] Newer versions of the WAG-9 feature full Insulated-gate bipolar transistor (IGBT) traction control; the debut model was the WAG-9 31248.

It is similar to the WAP-7 class locomotive but features a different gear ratio, which makes it suitable for heavy freight operations.

In November 1998, the Chittaranjan Locomotive Works (CLW) started producing these with indigenous components.

Like the WAP-5 units, the WAG-9 has GTO thyristor converters and three-phase asynchronous motors.

With its higher power, this locomotive has replaced WAG-7 which was the main electric loco before WAG-9's arrival.

Nowadays, it is quite common to see special passenger trains hauled by WAG-9 locomotives.

The decision to upgrade the power output of the WAG-9 was taken to partly meet the demands of the upcoming electrified Western Dedicated Freight Corridor (WDFC).

The upgraded locomotive class will also augment hauling capacity on the existing network of the Indian Railways.

The locomotive can run even in 100% humidity, or in deserts, where there is high saturation of conductive particles.