Transformer Rating Transformer Rating nhcf (Electrical) (OP) 12 Jul 17 01:16 What does transformer designation OA/FA-T indicate? This is from a database and not from the actual transformer nameplate. Not sure what the 'T' signifies. RE: Transformer Rating magoo2 (Electrical) 12 Jul 17 01:22 OA is the self-cooled rating FA is the fan cooled rating I don't know what the T indicates. RE: Transformer Rating nhcf (Electrical) (OP) 12 Jul 17 01:43 Yup. Maybe the T in the database is unrelated to the rating - I have not seen it before.