20kV, 866 A Earthing transformer

Earthing transformers provide a neutral point on the delta connected side of the main transformer. The phases are connected in a zigzag or interconnected star scheme and an auxiliary winding could be provided for an internal substation supply. If required an off-circuit tap-changer is supplied on the main windings. The most important factors in the design of these transformers are the Zero-sequence impedance and Short-circuit withstand duration which both are considered carefully in Iran Transfo products.