what is the use of earthing one end of tertiary delta winding

[arnabanindita]

What is the use of earthing one end of tertiary delta winding of an auto transformer? Does it help to detect earth fault in tertiary winding? If tertiary winding is not loaded is it necessary to earth tertiary winding?

 

[PowerfulStuff]

arnabanindita,
Earthing ensures that the tertiary winding does not float to an excessive voltage and damage insulation. Where the delta has load connected a separate neutral earthing transformer can be used to give balanced voltages and ensure a ground reference.

Regards,
Martin