What is the purpose of a grounding transformer?

[BINGMD]

What is the purpose of a grounding transfomrer?

My opinion is that

For an ungrounded system, a grounding transformer is added to provide a grounding source in order to make a grounding overcurrent relay trips a ground fault at the system, so that cables and surge arrestors will not bear overvotlage over their limits.

Also, it will provide a neutral connection.

Appreciate if you could provide any supporting documents.

Thank you,
Regards,
Bing

 

[cuky2000]

To find the purposes of grounding a transformer see the enclosed link

http://cuky2000.250free.com/Neutral_Grounded_1.jpg

 

[Hoxton]

See also the Areva T&D website and look for ftp://ftp.areva-td.com/NPAG/Chap17-280-315.pdf

Basically it is used to provide a high impedance in a compact form.