Grounding transformers can provide a grounding path for an ungrounded system or be utilized when the system’s neutral line fails and becomes unavailable. 

The reason for employing a grounding transformer (or) its functionalities are as follows:

When the transformer is grounded, reduce the magnitude of transient overvoltage.

Provide a reasonably low impedance grounding path for transformer such that the system’s neutral point remains at or near the ground potential.

Provide a current source during a line grounding failure.

In special cases, connect a phase-neutral load.