I have a 13800V to 600V 2MVA step-down transformer.
I need to megger test this unit, I have a megger good for 5KV and also a hi-pot DC tester (Megger brand).
I am unclear of how to make the physical connections between the transformer and the testers.
make sure the transformer is not connected to any thing like the potential transformer,than carry out
 usual insulation test between the frame and the connections terminations of the ht side.
 test between frame and the lv side terminations.
 test between ht terminations and LV terminations.
 test between phases at HT side
 test between phases at LV side.