The model name stands for broad-gauge (W), Diesel (D), Goods traffic (G) engine, 3,100 hp (3A) locomotive.

Despite the introduction of more modern types of locomotives like WDG-4 and electrification, a significant number are still in use, both in mainline and departmental duties.

From 2009 onward, they are equipped with Daulat Ram DBR, microprocessor control and an Auxiliary Power Unit (APU) in the short hood thus they bear external resemblance to the WDM-3D class.

Many units of this class has been named "Shakti" and can easily be recognized by their orange livery with cream stripe & lightning bolts.

Besides IR, WDG-3A are being use by private companies for industrial uses, thermal power plants, port trusts, etc.

Production was stopped in 2015 when advanced locomotives like the WDG-4D were built, thus rendering the ALCO platform obsolete.

[citation needed] They were an experimental technical variant of the WDG3A with an upgraded ALCO engine to output 3,200 hp, though it was unsuccessful, and all units were reverted to normal WDG-3A.

RDSO had suggested that such conversion would be possible with retaining the Motorized Truck assembly (which includes traction motors and drive side traction converters), computer controlled brakes (CCBs) and other relevant parts, suitably redesigning the under-frame and superstructure and adding the conversion kit.