I am developing the specs of a new paralleling transformer. Can you advise which documents can I use to help me with specs of CT settings to avoid saturation and settings of potential secondary PT for protection application?
If you are going to have identical protection relays as available with the existing transformer, you may refer to the same CT/VT specifications. Of course, you need to verify to make sure those who have sized those CT/VTs have not committed any mistake.
Generally, you refer the Protective relay technical manuals for the CT/VT parameter sizing formulas / information. If you know which make/model relay you pan to purchase, it is easier. Otherwise, you have to size the CT/VTs suitable for different make/model relays.