Insulation resistance busducts

[Opatiss]

I want to perform an insulation resistance test to the Isolated phase bus ducts.(megger 5KV)
There are VT connected in GCB copartment (star grounded primary and secondary)
Will they affect the value measured? Is it necessary to disconnect them primary?

 

[davidbeach]

If you leave the VTs connected, all your insulation resistance test will measure is the resistance of the VT and tell you nothing about the isophase bus.

 

[unclebob]

Removing the fuses would help