How to Wire a FT Switch in a Delta Connected CTs?

[Kiribanda]

Gentlemen,
Appreciate inputs on the following CT isolation issue.
During electromechanical relay time, the CTs in the wye side of any Dyn transformer were connected in delta (delta side wye connected) and wired to the interposing CTs. Since there is no common wire available for this delta connected CTs,how the FT isolation switch was wired to isolate & ground any CT? In other words in a delta connected set of CTs is grounding necessary? A typical 3-line diagram will be very helpful.

 

[davidbeach]

Grounding is certainly necessary, but that has nothing to do with the FT switch.

 

[JG2828]

Something like this?

 

[Kiribanda]

Thank you very much JG2828.It was the one I was expecting.