A. In some high rating transformers, one winding, in addition to the primary and secondary winding, is used. This is known as Tertiary Winding of Transformer. Because of this third winding, the transformer is called Three Winding Transformer. Advantages: 1. It reduces the unbalancing in the primary due to unbalancing in three phase load. 2. It redistributes the flow of fault current 3. To supply an auxiliary load in different voltage level in addition to its main secondary load.(station lighting and power) 4. As the tertiary winding is connected in delta formation in 3 winding transformer, it assists in limitation of fault current in the event of a short circuit from line to neutral.