Oil sample test of transformers

Location
Ras tanura
Occupation
Electrical inspector
If a transformer oil sample test was conducted during the Site Acceptance Test (SAT) but the transformer has remained de-energized for over six months, should another oil sample test be performed to check for potential contamination
 
If a transformer oil sample test was conducted during the Site Acceptance Test (SAT) but the transformer has remained de-energized for over six months, should another oil sample test be performed to check for potential contamination
The only contamination that could occur would be moisture absorption. Was the transformer stored with a nitrogen blanket?
 
If it’s ip66 rated, why you expecting contaminates?
When I used to work for the utility company we had a 2.5MVA unit that sat outside de-energized for 6 years. The oil sample was identical to the one pulled 10 years earlier when it was energized.
 
Transformer are installation on foundations already and not covered by blanket becuse they are IP66.
The nitrogen blanket is gas that is purposely introduced into the transformer. It provides a buffer so that air is not drawn into the transformer tank as the cooling liquid expands and contracts.
 
The nitrogen blanket is gas that is purposely introduced into the transformer. It provides a buffer so that air is not drawn into the transformer tank as the cooling liquid expands and contracts.
I would have to know the size to know if it has a N2 blanket. Only the substation transformers had N2.
 
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