There is one 40MVA oil cooled transformer (yet to comission), filled with 95% oil and we are trying to fill 5% Nitrogen (possitive pressure 4 psi) in that transformer so that there should not be any foreign component inside. But even though there is no leakage, nitrogen is not withstanding and vaccum is creating inside tank. Within a day or two pressure guage is showing 0. There is no breather for transformer, it wil fully airtight and outdoor type.
pls guide what to be done to maintain positive pressure inside transformer to avoid moisture/water/air entry.
Why is it soooo? Pls reply.